Aquat. Living Resour.
Volume 34, 2021
Special Issue - Ecological intensification: A new paragon for sustainable aquaculture
|Number of page(s)||12|
|Published online||05 August 2021|
Supplementation of biofloc in carp (Cyprinus carpio var. Communis) culture as a potential tool of resource management in aquaculture
Department of Aquaculture, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, Kolkata 700094, West Bengal, India
2 Department of Aquaculture, College of Fisheries, Guru Angad dev Veterinary and Animal Sciences University, Ludhiana 141004, Punjab, India
* Corresponding author: firstname.lastname@example.org
Handling Editor: Joel Aubin
Accepted: 15 July 2021
Supplementation of biofloc in rearing of common carp (Cyprinus carpio var. Communis (0.84 ± 0.003 g) was tested in replacing costly feed and environmental amelioration. Neem (Azadirachta indica) leave extract in biofloc media has beenknown to be beneficial in controlling pathogenic Vibrio sp. in brackish water shrimp. Two studies were conducted for 120 days in outdoor experimental cisterns with reduction of feed from 50% to 100%, with two biofloc media; without (Experiment 1; E1) and with neem extract (Experiment 2; E2). The experimental groups were: biofloc with feeding at 6% body weight (T1E1 and T1E2), biofloc with feeding at 3% body weight (T2E1 and T2E2), biofloc without feeding (T3E1 and T3E2), feeding at 6% body weight (C1) and only biofloc (C2E1 and C2E2). Absolute weight gain in T2E1 (9.96 g) was 8.23% and in T2E2 (9.56 g) was 4.39% higher than C1 (9.14). In spite of 5.04% and 13.98% higher growth respectively in T1E1 (10.50 g) and T1E2 (11.66 g) than C1 (9.97 g), BFT could not compensate the total withdrawal of feed (T3E1 and T3E2) and resulted in 22.22% to 33.33% mortality in T3E2 and T3E1 respectively. Under identical feeding regime, FCR was improved by 52.57% to 53.76% in T2E1 (1.84) and 48.71% to 51.23% in T2E2 (1.99) compared to T1E1 (3.98) and T1E2 (4.08). Absolute weight gain in T2E1 was 8.97 times and in T2E2 was 4.63 times higher than C1. In spite of 18.54% and 7.26% higher growth respectively in T1E1 and T1E2 than C1, BFT could not compensate the total withdrawal of feed (T3E1 and T3E2) and resulted in 22.22% to 33.33% mortality in T3E2 and T3E1 respectively. Under identical feeding regime, FCR was improved by 52.57% to 53.76% in T2E1 and 48.71% to 51.23% in T2E2 compared to T1E1 and T1E2 respectively. Increased N: P ratio of water and soil in E2 favoured fish growth. Neem leave extract in biofloc media should be judicious as it may cause nitrification inhibition.
Key words: Biofloc / Azadirachta indica / Cyprinus carpio var. Communis / feed conversion ratio / mineralizing microbes
© EDP Sciences 2021
Globally, common carp (Cyprinus carpio L.) is the fourth most important cultured fish with a share of 7.7% of total aquaculture fish production (FAO, 2020). Moreover, common carp culture practice is changing from semi-intensive form to more intensive systems (Bakhshi et al., 2018). High stocking density can lead to stress related issues in fish, which are the major concerns in the current context due to high incidence of disease-causing harmful pathogen, low growth and feed utilization performance (Xie et al., 2018). Intensification of aquaculture has been warranted because of increasing per capita demand, which eventually led to increase in pollution load especially in tropical carp culture sector (Mpeza et al., 2013; Tavakol et al., 2017).
Intensification of aquaculture has been warranted because of increasing per capita demand, which eventually led to increase in pollution load especially in tropical carp culture sector (Mpeza et al., 2013; Tavakol et al., 2017). Globally, common carp (Cyprinus carpio L.) is the fourth most important cultured fish with ashare of 7.7% of total aquaculture fish production (FAO, 2020). Moreover, common carp culture practice is changing from semi-intensive form to more intensive systems (Bakhshi et al., 2018). High stocking density can lead to stress related issues in fish which are the major concernsin the current context due to high incidence of disease-causing harmful pathogen, lowgrowth and feed utilization performance (Xie et al., 2018).
In recent times, biofloc technology (BFT) is getting more attention in aquaculture due to its greater effectiveness in terms of sustainable production (Ahmed et al., 2017) through improvement of water quality, feed efficiency and immunity of fish (Crab et al., 2012; Mirzakhani et al., 2019). Moreover, the technology has a huge potential to conserve land and water and to promote heterotrohic feed resources (Ekasari and Maryam, 2012). Also, the main principle of BFT is based on more efficient use of nutrient input in limited or zero water exchange (Avnimelech, 1999). BFT is mainly focused on prevention of feed-borne toxic nitrogen metabolites (NH3, NO2–, etc.) accumulation through stimulation of heterotrophic microbes by manipulation of carbon/nitrogen ratio (C:N) (Avnimelech, 2009). High proliferation ability of heterotrophic bacteria results in formation offlocs, so called biofloc which contains heterogenous populations of heterotrophic microbes, fungi, plankton, protozoa, nematodes, organic polymers and dead cells (De Schryver et al., 2008; Avnimelech, 2009; Ekasari et al., 2010). Regular consumption of floc by cultured fish can increase feed efficiency (Xu et al., 2012), resource productivity (Wei et al., 2016), and bio-security in aquaculture (Pérez-Fuentes et al., 2016). Also, the biofloc can ameliorate water quality and improve growth performance of common carp under zero water exchange system (Bakhshi et al., 2018). Schneider et al. (2005) reported that 7–13% of improvement nitrogen retention can be possible through optimization of C:N ratio in biofloc system. Biofloc can also favor phosphorus mineralization and the mineralization process becomes limited in maintaining the balance between available nitrogen: phosphorus beyond 0.065 mg l−1 (Dinda et al., 2019).
The successful culture of fish in biofloc supplemented system has been reported in common carp (Hargreaves, 2013), channel catfish (Green et al., 2014), Nile tilapia (Ekasari et al., 2015) with promising findings. Mahanand et al. (2013) reported that biofloc technology could able to enhance the good water quality, natural food availability and growth performance of common carp in high-intensity systems. The omnivorous common carp is compatible to ingest and digest bioflocs and able to tolerate high concentrations of suspended material in the water, and low concentrations of oxygen and stress when cultured in intensive BFT system (Najdegerami et al., 2016).
Various medicinal herbs are used in aquaculture to reduce or replace chemicals and drugsdue todevelopment of antibiotic resistance of bacteria (Cabello, 2006). Application of different parts of neem (Azadirachta indica) in aquaculture has become a means to control pathogen and disease (Martinez, 2002) to benefit from its bioactive compounds (azadirachtin and nimbin) (Biswas et al., 2002). The presence of natural bioactive compounds, namely azadirachtin in neem highly influence the phosphatase activity (Gopal et al., 2007) and to some extent inhibit the nitrification process in aquaculture (Das et al., 2018). Dinda et al. (2019) reported that neem based biofloc system can inhibit nitrification process in culture of common carp. However, farmers in India have been recently using neem leaves extract as herbal therapeutants in biofloc supplemented aquaculture of both finfish and shrimps (Mandal and Das, 2018, Dinda et al., 2019).
Therefore, the present study was aimed to evaluate the impact of use of biofloc media in biofloc system for culture of common carp fingerlings on growth, proximate composition, water quality and feeding performance at different feeding levels with two experiments to evaluate the supplemental neem extract in culture environment.
The present study was conducted in an outdoor experimental system consisting of cylindrical cemented cistern (Area: 0.18 m2; Volume: 180 liters) (Cyprinus carpio var. Communis) at Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, Chakgaria, Panchasayar, Kolkata-700094 (22°28′46″N and 88°24′4″E). Two biofloc medium experiments were conducted simultaneously without (E1) and with neem extract (E2). In both main treatment blocs, experimental cisterns were grouped into biofloc with feeding level at 6% body weight (T1E1 and T1E2), biofloc with feeding level at 3% body weight (T2E1 and T2E2), biofloc without feeding (T3E1 and T3E2), no biofloc with feeding at 6% body weight (Control 1; C1). Another control treatment without fish and feed but under BFT in both with and without neem extract was also employed (Control 2; C2E1 and C2E2). All the treatments were triplicated cisterns (Tab. 1). A commercial pellet feed with 25.04% crude protein was purchased from the local market and provided to fish once daily (9-00 AM) at pre-determined levels for 120 days. Usually, the protein requirement in fish ranged from 25 to 45% (Davies and Gouveia, 2010), and as the test fish were reared in manured system, 25.04% crude protein feed was provided as supplemental feed.
All cisterns were provided with 15 cm of soil base and filled with ground water (pH: 7.5) prior to stocking experimental fish. The experimental units were manured with semi-decomposed cow dung at a dose of 10,000 kg ha−1. After seven days of manuring, liming and fertilization were performed (agricultural lime at 200 kg ha−1; single super phosphate at 20 kg ha−1 and urea at 40 kg ha−1). The cisterns were covered with fine mosquito net and kept undisturbed for another seven days. Continuous aeration was provided to each cistern during entire period of the experiments. When the water color turned into bluish-green, we assumed enough planktonic development to stock experimental fish. Fifteen healthy fingerlings of common carp (0.85 ± 0.05 g, 4.65 ± 0.04 cm) were acclimatized for seven days and stocked with 83 nos m−2 to each cistern in both experimental blocks (E1 and E2), except C2E1 and C2E2. Required volume of water (5–10% of total volume of cistern) was added to both the systems to maintain the water level due to evaporation and sampling loss.
Experimental design for the present study.
Two different starting biofloc media, without (M1) and with neem (M2) were prepared through an aerobic process in two separate glass jars (50 liters each) provided with constant aeration (Tab. 2). Within the media composition, sugarcane molasses was used as major external carbon source, whereas, boiled rice water neem leaves extract was considered as low carbon sources for biofloc media development. Supplemental ammonium sulfate was added as source of ammonia at required quantity during the preparation of media. The M1 media composition was used for first experiment (E1) and M2 medium composition was used for second experiment (E2) for in situ development of biofloc. The biofloc medium of 15 ml per cistern was applied over the water surface of respective treatments of both E1 and E2 once daily (10–11 AM) in the morning for the first 45 days of experiment as practiced by the shrimp farmers of the district East Midnapur, West Bengal, India. The shrimp farmers usually apply 100 liters biofloc medium in 1200 m3 shrimp pond for first 45 days of culture period in biofloc system. The aim of the ex-situ preparation of biofloc media (M1 and M2) was to develop heterotrophic bacterial populations and subsequent biofloc in situ in the cisterns.
Composition of biofloc media used in present study.
Sugarcane molasses was used as an external organic carbon source to achieve the required C: N ratios by calculating according to the formula given by Avnimelech (2009). Diluted molasses was applied in respective treatments daily at 10.30 hr. with higher aeration to facilitate uniform mixing in water. Initially, C: N input ratios were calculated based on the carbon-nitrogen contents of the feed and the carbon content of the molasses. The commercial feed (25.04% crude protein) for C. carpio had a calculated C: N ratio of 9:1, assuming the feed had 50% carbon and 5.60% of nitrogen (Xu et al., 2018). About 0.76 ml to 1.32 ml molasses per gram feed was added to maintain C: N ratio between 12:1–15:1 in the respective treatment groups. However, for T3E1 and T3E2, only sugarcane molasses was the sole source of carbon that has been taken into account in absence of feed supplementation.
Collection of water and soil samples were performed aseptically in sterilized polypropylene bottles (200 ml) at 15 days intervals from each cisterns for physico-chemical and bacteriological analyses following the methods described by Arulmoorthy et al. (2014). Soil samples were collected using mini hand grab-sampler and pooled together by thorough mixing, air dried, pulverized with pestle and mortar, sieved through a 150 µm mesh sieve and stored in labeled polythene packets for analyses. Biofloc samples were collected at 15 days interval by using Imhoff cone (1 liter capacity) for proximate composition analysis from the respective treatments and filtered through 100- μm mesh. The cumulative biofloc samples were dried in an oven at 102 °C temperature until constant weight and then preserved in a refrigerator. Biofloc samples were ground and processed for proximate analysis. For carcass analysis of experimental fish, fish was collected at the end of the experiment from each treatment and anesthetized with clove oil (50 µl l−1 of water) followed by dissection whereas intestine was removed and whole fish was subjected for proximate composition.
Water temperature and pH (HI-98127) and total dissolved solids (TDS) (Eutech − N374) were measured in-situ. Water temperature was measured using the same pH meter. Standard methodologies were followed for estimation of dissolved oxygen (DO), biological oxygen demand (BOD1), total alkalinity (TA), total hardness (TH), ortho-phosphorus (Ortho-P), ammonia-nitrogen (NH3-N), nitrite-nitrogen (NO2-N) and nitrate-nitrogen (NO3-N) of water (Wetzel and Likens, 1991; APHA, 1995). Soil pH, organic carbon (SOC), available nitrogen (SAN) and available phosphorus (SAP) were determined following the methods described by Jackson (1959).
Proximate analyses of experimental feed (Tab. 3) and biofloc (on dry matter basis) (Tab. 4) were performed as per the standard method of AOAC (2005). Dried biofloc samples were ground and processed for proximate analysis. The level of moisture was determined in hot air oven at 105 °C temperature for overnight until constant weight obtained. Crude protein (CP) and ether extract (EE) were estimated using micro-Kjeldahl method (KEL PLUS, Pelican Equipments, India) and Soxhlet extraction method (SOCS PLUS, Pelican Equipments, India), respectively. Crude fiber (CF) of the diets (fat free samples) was analyzed by using FIBRA PLUS (Pelican Equipments, India). The dried feed and whole fish sample were subjected to 550 °C for 5 h in a Muffle furnace (Macro Scientific, India) to measure the total ash (TA) content. The nitrogen-free extract (NFE) of the diets was calculated using following formulae: Nitrogen-free extract (NFE, g kg−1) = [1000 – (g CP kg−1 + g CF kg−1 + g TA kg−1 + gCFkg−1)]. Digestible energy (DE) of the diets was calculated as per the following formula given by Halver (1976): DE (kcal 100 g−1) = [4 × CP (g 100 g−1) + 9 × EE (g 100 g−1) +4 × NFE (g 100 g−1)]. The protein (P) to energy (E) ratio was calculated by using following formula: P:E (mg protein. kcal DE−1) = (CP% × 1000)/DE. Gross energy (GE) of the diet was measured by an automated bomb calorimeter (5E-AC/PL; Changsha Kaiyuan Instruments Corporation Pvt. Ltd., China) and expressed in kcal 100 g−1. Carcass composition of the experimental fish was calculated on % wet weight basis.
Proximate composition of commercial feeds used for C. carpio.
Growth response and mortality rate (Mean ± Standard error) of C. carpio in biofloc system.
Enumeration of aerobic heterotrophic bacteria (THB) was done by following the standard methods (APHA, 1995). Estimation of nitrogen fixing bacteria (NFB), ammonifying bacteria (AB), ammonia oxidizing bacteria (AOB) and denitrifying bacteria (DNB) were done by following the methods described by Alexander (1978), phosphate solubilizing bacteria (PSB) by the method of Subba-Rao (1977) and cellulose decomposing bacteria (CDB) the method of Sarkhel and Das (2005).
Fish growth was recorded with fortnightly weighings. Absolute weight gain (AWG), specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER), apparent net protein utilization (ANPU%) were calculated as follows:
Feed conversion ratio = [Total dry feed fed (dry weight in g) / Weight gain (wet weight in g)]
Data were submitted to the two way analysis of variance (Montgomery, 2001) with interactions. This has been applied to test the significance in difference among the treatments with regards to the efficacy of biofloc over feed based treatment and interaction of neem extract in neem based biofloc over all the treatments. Post-hoc analysis (Duncan's multiple range test; DMRT) were applied to find out the homogeneity among the mean of every possible pair of treatment combinations (SPSS Statistics v. 20.0). The statistical model applied for the two way ANOVA was: Yijk = Ti + Cj + (T*C)ij + eijk; where, Ti = treatment at ith number, Cj = condition at jth number, eijk= error. Pearson's correlation coefficient was applied to examine relationship between available nutrient parameters in soil and with selective physico-chemical parameters.
All the parameters related to growth and nutrient utilization including body weight, AWG, SGR, feed intake, FCR, PER and ANPU were found to be significantly (P < 0.05) affected by biofloc application and feeding level in both E1 and E2 (Tab. 4). Growth rate increment of fish was significantly (P < 0.05) less in T3E1 (1.53 ± 0.24%) and T3E2 (1.52 ± 0.26%) compared to T1E1, T2E1, T1E2 and T2E2 (2.09–2.18%). The SGR increased in all the treatment groups except C1E1 and C1E2 with highest and lowest absolute growth attained in T2E1 and T3E1, and, T1E2 and T3E2 respectively. Moreover, significantly higher body weight was attained in T1E2 (11.66 ± 1.31 g) compared to T1E1 (10.50 ± 1.15 g). Though treatment difference remained significant (P < 0.05), insignificant difference (P > 0.05) was observed between T1E1 and T2E1; T1E2 and T2E2. Similar trends were also observed in ABG and SGR in fish. Feed intake capacity was naturally lower both in T2E1 and T1E2 compared to control due to predetermined feeding level. FCR was higher in T1E1 and T1E2 and, lower in T2E1 and T2E2 compared to C1. PER and ANPU significantly increased in T2E1 and T2E2 as compared to T1E1, T1E2 and C1.
However, biofloc alone could not be sufficient in supporting growth and survival rates of the test fish either in E1 or in E2 were lower with mortality rates 33.33% and 22.22% in T3E1 and T3E2 respectively (Fig. 1). Biofloc volume was highest in T1E2 and was lowest in C2E1 (Tab. 5) with significant (P < 0.05) difference among the treatments of both E1 and E2.
Analyses of proximate composition of biofloc indicated that crude protein content was increased, whereas, crude lipid, carbohydrate and ash content declined in all the treatments during the study period. Mean protein content ranged from 27.98% to 33.55% and was highest in T1E2 and lowest in C2E1. Carbohydrate content ranged from 4.96% to 9.87% and significantly (P < 0.05) differed among the treatments. Lipid content ranged from 1.06% to 3.02% and significantly differed (P < 0.05) among the treatments (Tab. 5). The calculated DE value was higher in the treatments of E2 compared to E1. Mean DE value ranged from 369.24–384.01 kcal. 100 g−1 and significantly differed among the treatments (P < 0.05; Tab. 4). Mean P:E ratio ranged from 7.40–8.84 mg protein. kcal DE−1 and significantly differed among the treatments (P < 0.05; Tab. 4).
Water temperature ranged between 25 and 27 °C during the study period. Water and soil pH remained alkaline in all the treatment groups of both E1 and E2 throughout the study period and ranged between 7.03–7.67 and 7.13–7.61 respectively (Tab. 6). NH3-N of water gradually decreased up to 60th day followed by increasing trend in all the treatment groups except in C1 (Fig. 2). NH3-N in general, was higher in all the treatment groups of E2 compared to the treatment groups of E1 and it was significantly higher both in T1E1, T2E1; T1E2 and T2E2 as compared to C1. The mean NH3-N concentration ranged from 0.086 mgl−1 to 0.191 mgl−1 and significantly differed among the treatments (P < 0.05; Tab. 6). NO2-N of water gradually increased in all the treatment groups of both E1 and E2 with highest concentration recorded in T1E1 and lowest in C2E1 and C2E2 (Fig. 3). The mean NO2-N concentration ranged from 0.002 mgl−1 to 0.007 mgl−1 and significantly differed among the treatments (P < 0.05; Tab. 6). NO3-N of water remained significantly higher in the treatments of E2 compared to E1 (Fig. 4). The mean NO3-N concentration ranged from 0.173 mgl−1 to 0.339 mgl−1 and significantly differed among the treatments (P < 0.05; Tab. 6).
Total available nitrogen (TAN) continued to increase in all the treatment groups of both E1 and E2 (Fig. 5) and it was comparatively higher in the treatments with neem extract (E2) than E1. The mean TAN ranged from 0.260 mgl−1 to 0.535 mgl−1 and significantly differed among the treatments (P < 0.05; Tab. 6). Ortho-phosphate of water gradually increased in T1E1, T2E1, T1E2 and T2E2, whereas, the trend gradually declined in T3E1 and T3E2 (Fig. 6). However, it was comparatively higher in the biofloc medium without neem compared to E2 (medium with neem extract). The mean ortho-phosphate concentrations ranged from 0.05 mgl−1 to 0.081 mgl−1 and significantly differed among the treatments in both E1 and E2 (P < 0.05; Tab. 6). Significant difference in the values of N: P ratio was observed in water and soil of both E1 and E2 (P < 0.05; Tab. 6).
Total aerobic heterotrophic bacterial population (THB) in water gradually increased in all the treatments with highly significant treatments difference (P < 0.05) in E1 and E2. The highest population was encountered 6.97 CFU (No ×103ml−1) in T1E1 and 6.16 CFU (No × 103 ml−1) in T1E2 which was 9.56–39.71% and 9.31–39.18% higher than rest of the treatments in water and soil, respectively in E1 and E2 (Figs. 7 and 8). THB, AB, AOB, NFB, DNB, CDB and PSB populations were higher in the treatment groups in E1 compared to E2 (Tab. 7). The AB, AOB, NFB and DNB populations increased gradually followed by a declining trend from 90th day in all the treatment groups except in C2E1 and C2E2 in which such decline was encountered from 45th day onwardsin both water and soil. The mean density of AB ranged from 1.88 to 4.44 CFU (No × 103 ml−1) in water and 3.25 to 4.99 CFU (No × 103 ml−1) in soil with significant difference among the treatments of both E1 and E2 (P < 0.05; Tab. 7).
The mean population of AOB ranged from 2.21 to 5.67 CFU (No × 103 ml−1) in water and 3.06 to 6.27 CFU (No × 103 ml−1) in soil with significant difference among the treatment groups of both E1 and E2 (P < 0.05; Tab. 7). The mean density of NFB ranged from 2.32 to 5.31 CFU (No × 103 ml−1) in water and 3.15 to 6.23 CFU (No ×103 ml−1) in soil with significant difference among the treatment groups of both E1 and E2 (P < 0.05; Tab. 7). The mean population density of DNB ranged from 2.71 to 5.37 CFU (No × 103 ml––1) in water and 2.93 to 6.13 CFU (No × 103 ml−1) in soil with significant difference among the treatment groups of both E1 and E2 (P < 0.05; Tab. 7). CDB population in water and soil continuously increased in the entire treatment group except in T3E1, T3E2, C2E1 and C2E2, it declined during 2nd half of the study period. The mean population of CDB ranged from 3.43 to 5.81 CFU (No ×103 ml−1) in water and 3.50 to 5.84 CFU (No × 103 ml−1) in soil with significant difference among the treatments of both E1 and E2 (P < 0.05; Tab. 7). PSB population in water and soil tended to increase in all the treatments upto 60th day of experiment period, whereas, the population declined in C2E1 and C2E2 during the 2nd half of the study period. The mean population of PSB ranged from 2.43 to 4.88 CFU (No ×103 ml−1) in water and 3.07 to 5.40 CFU (No × 103 ml−1) in soil with significant difference among the treatments of both E1 and E2 (P < 0.05; Tab. 7).
Mortality rate (%) of C. carpio in different treatments.
Biofloc volume and proximate composition of biofloc (% dry weight basis) inboth E1 and E2.
Physico-chemical parameters (mean ± standard error) of water and soil in C. carpio biofloc system.
Temporal changes in NH3-N of water in all the treatments of E1 and E2.
Temporal changes in NO2-N of water inall the treatments of E1 and E2.
Temporal changes in NO3-N ofwaterin all the treatments of E1 and E2.
Temporal changes in TAN of water inall the treatment groups in E1 and E2.
Temporal changes in ortho-P ofwaterin all the treatments of E1 and E2.
Temporal changes of THB in water inthe treatments of E1 and E2.
Temporal changes of THB in soil in the treatments of E1 and E2.
Microbial populations in the both experiments E1 and E2.
As the absolute weight gain of the test carp over the initial weight was 2.79 and 5.17 times in only biofloc supported treatment without feed supplementation (T3E2 and T3E1), it was indicative of the potential of biofloc in supporting Cyprinus carpio L. However, it was higher respectively by 1.46 and 1.18 times where feed was applied at 6% (T1E1 and T1E2) and 3% (T2E1 and T2E2) of body weight daily compared to only neem supplemented biofloc applied treatment (T3E2) against 1.17 and 1.24 times in without neem supplemented treatments (T3E1). However, biofloc alone could not be sufficient in supporting growth and survival of fish in either of the media with or without neem as the mortality rate was substantial (22.22 to 33.33%) in the latter, which may be due to not application of biofloc in C2E1 and C2E2 in after first 45 days of total experiment period. The findings are in agreement with Dinda et al. (2019) who reported biofloc alone is insufficient to guarantee the level of growth and survival required for high-density fish farming.
A comparison of the treatments T1E1, T1E2, and C1 on 6% feeding level with and without BFT respectively revealed that BFT provided 18.54% and 7.26% more growth in T1E1 and T1E2 as compared to C1 in presence and absence of neem leave extract, suggesting that BFT can be quite efficient in increasing growth and productivity in common carp. The findings are in conformity with the results of earlier studies (Pérez-Fuentes et al., 2013; Kamilya et al., 2017; Dinda et al., 2019). As body weight, absolute weight gain and specific growth rate differed significantly (P < 0.05) among the treatments with insignificant (P > 0.05) difference between with (E2) and without neem extract (E1) biofloc without feed (T3E2 and T3E1, respectively), there was no effect of neem extract in the biofloc medium in contributing fish growth. However, insignificant difference between T1E1 and T2E1 and, T1E1 and T2E2 established that presence of neem extract under feeding regime supported 50% feed reduction (T2E1 and T2E2) without any significant decrease in the fish growth. Therefore, neem supplementation in BFT with feed supplementation appeared to perform better in terms of weight gain and reduction of supplemental feed cost.
However, FCR was significantly higher by 2.16 and 2.05 times in T1E1 and T1E2 compared to T2E1 and T2E2 (Tab. 5). Therefore, under any of the biofloc treatments, production cost towards feed could be reduced at least by 50% without significant decrease in fish growth. Moreover, under identical feeding regime (6% body weight day−1), compared to C1, FCR was slightly improved by 2.66% and 5.01% in both T1E1 and T1E2. Though, FCR significantly differed among the treatments (P < 0.05), presence (E2) or absence of neem extract (E1) under 50% reduction of feed in T2E1 and T2E2 had no significant impact on FCR (P > 0.05). Moreover, neem extract in biofloc under normal feeding rate (T1E1 and T1E2) did not exert any impact on PER as difference with C1 was insignificant (P > 0.05); though under reduced feeding rate, such comparison was significant (P < 0.05). Therefore, in-situ biofloc has substantial protein sparing capacity which could be able to substantially scale down the rate of costly feed application (Xu et al., 2012).
Reduction of pH with either of the biofloc treatments in comparison to the control was due to inorganic carbon consumption by autotrophic and heterotrophic bacteria that form the microbial biomass (Pérez-Fuentes et al., 2016; Martins et al., 2017). Martínez et al. (2014) reported that organic loading resulted in decline of pH in water. Such reduction in water pH resulted in a decline of alkalinity during the corresponding phase as they were positively correlated (r = 0.71 and 0.89). Moreover, because of organic loading during the first half, BOD1 remained high and it declined after the biofloc application stopped after 45 days. Several studies (Das and Jana, 2003; Schryver et al., 2008; Martínez et al., 2014) also recorded such situation where organic loading had a direct bearing upon the BOD load of the system. Initially, total hardness of water was fairly high (624–655 mg l−1), however, as the culture systems matured, there were drastic falls of such hardness and became congenial (240–350 mgl−1) for fish culture after one month of investigation. Total dissolved solids and conductivity of water in either of the biofloc system increased over time because of the enrichment of organic loading and nutrients in the medium compared to the control treatment. This has been corroborated with the fact that concentration of any of the inorganic nutrients also increased simultaneously in those treatments. Wu and Chou (2003) also reported a direct relationship between nutrient loading and conductivity of water.
Significant increase in all the nutrients (TAN, NH3-N, NO3-N and ortho-P) in the treatments where feed was applied irrespective of the types of biofloc was perhaps because of the metabolic wastes and decomposition of the uneaten feed and dead materials. As the applied feed contained 25% crude protein, substantial quantity of ammonia might have been resulted in because of the de-amination of amino acids in energy metabolism. Adhikari et al. (2014) have demonstrated that supplementary feed acted as a source of both nitrogen and phosphorus in fish culture systems. Inorganic nitrogen concentration of water in BFT treatments with neem were comparatively higher compared with those without neem, indicating that supplemental nitrogen input could be the case through the boiled neem leaves in the medium (Vinaygam et al., 2006). BFT application also proved to be efficient in increasing the mineralization potential of the systems as evidenced from the more rate and potential of transformation of any of the inorganic forms of nitrogen in BFT treatments. However, neem supplementation in BFT treatments displayed negative impacts upon nitrogen mineralizing microbes as evidenced from the significantly less population size compared to the treatments without neem and treatment differences were significant (P < 0.05). However, positive relationship was established in the nutrient status between any of the biofloc supplemented treatment groups and C1. The relationship between total inorganic nitrogen (TIN) and N:P of water was established with a strong positive relationship in any of the bioflocs identical to C1 where fish were reared with supplementary feed in absence of biofloc (R2 = 0.985 for T1E1; R2 = 0.962 for T2E1; R2 = 0.985 for T3E1; R2 = 0.945 for C2E1; R2 = 0.967 for T1E2; R2 = 0.968 for T2E2; R2 = 0.963 for T3E2 and R2 = 0.957 for C2E2).
As expected soil organic carbon increased substantially in biofloc supported systems particularly feed was appliedsource of carbon. Such increase in organic pool in the sediment might have supported the phosphate mineralizing microbial community and resulted in a strong positive relationship between organic carbon and available phosphorus in soil of E1 and E2 (R2 = 0.677 for T1E1; R2 = 0.640 for T2E1; R2 = 0.709 for T1E2 and R2 = 0.743 for T2E2). However, such relationship was also established in C1 with 6% feed application in absence of biofloc with much higher degree of significance (87%).
Higher abundance of aerobic heterotrophic bacterial population in all the treatment groups of both BFT (E1 and E2) confirmed that external source of carbon enhanced such population through amelioration of C:N ratio which in turn supported higher production of biofloc and microbial protein as well. Compared to neem supplemented biofloc system, higher abundance of THB in biofloc medium without neem validated the antimicrobial properties of neem leaves in biofloc medium might have inhibited nitrification which resulted in low N:P ratio. This in accordance with the earlier findings of Das (2008), who reported a strong nitrifying inhibition of neem extract in aquatic productions systems. However, in general, strong positive relationships were established between total available-N (TAN) and TAN:P of water and SAN and SAN : SAP in soil maintained strong positive relationships (R2 = 0.77–0.97) (Fig. 9). The increasing trend of N:P ratio in both BFT systems supported nitrogen and phosphorus mineralization, being in conformity with earlier findings of Ahmad et al., (2017).
Linear relationship between TAN vs TAN:P ratio in water and SAN vs SAN:SAP ratio in soil in neem supplemented biofloc (E2) system.
The findings of the study strongly indicated the potential of BFT in reduction of dependence on compound feed in common carp. The neem (Azadirachta indica) supplementation in BFT improved the ecological health of the culture system with regards to physico-chemical and nutritional properties of water and soil. Besides, the present study concluded that heterotrophic potential within the systems with biofloc application with or without neem supplementation has been augmented excepting nitrogen mineralizers in some cases. However, application of neem leave extract in preparation of biofloc media should be judicious as it can limit nitrification.
Authors acknowledges the owner of shrimp culture ponds, East Midnapur, West Bengal, India and the laboratory facilities provided by the Department of Aquaculture, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, Kolkata, India.
- Adhikari S, Sahu BC, Mahapatra AS, Dey L. 2014. Nutrient budgets and effluent characteristics in Giant freshwater prawn (Macrobrachium rosenbergii) culture ponds. Bull Environ Contamin Toxicol 92: 509–513. [Google Scholar]
- Ahmad I, Babitha Rani AM, Verma AK, Maqsood M. 2017. Biofloc technology: an emerging avenue in aquatic animal healthcare and nutrition. Aquac Int 25:1215–26. [Google Scholar]
- Alexander M. 1978. Introduction to soil microbiology. 2nd Edn. Willey Eastern Limited, New Delhi. p. 467. [Google Scholar]
- AOAC. 2005. Official Methods of Analysis, 18th edition. Gaithersburg, MD: Association of Official Analytical Chemists International. [Google Scholar]
- APHA. 1995. Standard Methods for the Examination of Water and Wastewater. 19th edition, New York: American Public Health Association Inc. [Google Scholar]
- Arulmoorthy MP, Karunakaran K, Vignesh R, Vasudevan S, Srinivasan M. 2014. Identification and antimicrobial potential of bioluminescent bacteria isolated from the mangrove ecosystem of the Roach Park, Tuticorin, South East coast of India. BMR Microbiol 1: 1–15. [Google Scholar]
- Avnimelech Y. 1999. Carbon ⁄ nitrogen ratio as a control element in aquaculture systems. Aquaculture 176: 227–235. [Google Scholar]
- Avnimelech Y. 2009. Biofloc Technology − A Practical Guide Book. The World Aquaculture Society, Baton Rouge, Louisiana, United States. pp 182. [Google Scholar]
- Bakhshi F, Najdegerami EH, Manaffar R, Tukmechi A, Farah KR. 2018. Use of different carbon sources for the biofloc system during the grow-out culture of common carp (Cyprinus carpio L.) fingerlings. Aquaculture 484: 259–267. [Google Scholar]
- Biswas K, Chattopadhyay I, Banerjee RK, Bandyopadhyay U. 2002. Biological activities and medicinal properties of neem (Azadirachta indica). Curr Sci 82: 1336–1345. [Google Scholar]
- Cabello FC. 2006. Heavy use of prophylactic antibiotics in aquaculture: a growing problem for human and animal health and for the environment. Environ Microbiol 8: 1137–1144. [Google Scholar]
- Crab R, Defoirdt T, Bossier P, Verstraete W. 2012. Biofloc technology in aquaculture: beneficial effects and future challenges. Aquaculture 356–357: 351–356. [Google Scholar]
- Das S. 2008. Effects of neem (Azadirachta indica, L.) Seed cake on certain bio-geo-chemicalcycling microbes and fish growth. Master's Thesis, West Bengal University of Animal and Fishery Sciences, Kolkata, West Bengal, India. [Google Scholar]
- Das SK, Das S, Mandal A, Dinda R. 2018. Impact of neem (Azadirachta indica A. Juss) seed cake upon selective nutrient cycling bacterial population in fish culture. J Appl Aquac 30: 353–365. [Google Scholar]
- Das SK, Jana BB. 2003. Pond fertilization regimen: State-of-the-art. J Appl Aquac 13: 35–66. [Google Scholar]
- Davies SJ, Gouveia A. 2010. Response of common carp fry fed diets containing a pea seed meal (Pisum sativum) subjected to different thermal processing methods. Aquaculture 305: 117–123. [Google Scholar]
- De Schryver P, Crab R, Defoirdt T, Boon N, Verstraete W. 2008. The basics of bio-flocs technology: the added value for aquaculture. Aquaculture 277: 125–137. [Google Scholar]
- Dinda R, Das SK, Mandal A. 2019. Neem (Azadirachta indica A. Juss) supplemented biofloc medium as alternative feed in common carp (Cyprinus carpio var. communis L.) culture. J Appl Aquac 00: 1–19 [Google Scholar]
- Ekasari J, Crab R, Verstraete W. 2010. Primary nutritional content of bio-flocs cultured with different organic carbon sources and salinity. HAYATI J Biosci 17:125–130. [Google Scholar]
- Ekasari J, Maryam S. 2012. Evaluation of biofloc technology application on water quality and production performance of red tilapia Oreochromis sp. cultured at different stocking densities. HAYATI J Biosci 19: 73–80. [Google Scholar]
- Ekasari J, Rivandi DR, Firdausi AP, Surawidjaja EH, Zairin M, Bossier P. 2015. Biofloc technology positively affects Nile tilapia (Oreochromis niloticus) larvae performance. Aquaculture 441. [Google Scholar]
- FAO. 2020. The State of World Fisheries and Aquaculture 2020. Sustainability in action. Rome. [Google Scholar]
- Gopal M, Gupta A, Arunachalam V, Magu SP. 2007. Impact of Azadirachtin, an insecticidal allelochemical from neem on soil microflora, enzyme and respiratory activities. Bioresour Technol 98: 3154–3158. [PubMed] [Google Scholar]
- Green BW, Schrader KK, Perschbacher PW. 2014. Effect of stocking biomass on solids, phytoplankton communities, common off-flavors, and production parameters in a channel catfish biofloc technology production system. Aquacult Res 45: 1442–1458. [Google Scholar]
- Hargreaves JA. 2013. Biofloc production systems for aquaculture. Southern Regl Aquacult Center 4503: 1–11. [Google Scholar]
- Halver JE. 1976. The nutritional requirements of cultivated warm water and cold water fishspecies. Paper no. 31, FAO Tech. Conf. in Aquaculture., May 26-June 2. p. 9. [Google Scholar]
- Jackson ML. 1959. Soil chemical analysis. Verlag: Prentice Hall, Inc., Englewood Cliffs, NJ, 498 S. DM 39.40 [Google Scholar]
- Kamilya D, Debbarma M, Pal P, Kheti B, Sarkar S, Singh ST. 2017. Biofloc technology application in indoor culture of Labeo rohita (Hamilton, 1822) fingerlings: the effects on inorganic nitrogen control, growth and immunity. Chemosphere 182: 8–14. [Google Scholar]
- Mahanand SS, Moulick S, Rao PS. 2013. Water quality and growth of Rohu, Labeo rohita, in a biofloc system. J Appl Aquac 25: 121–131. [Google Scholar]
- Mandal A, Das SK. 2018. Comparative efficacy of neem (Azadirachta indica) and non-neem supplemented biofloc media in controlling the harmful luminescent bacteria in natural pond culture of Litopenaeus vannaemei. Aquaculture 492: 157–163. [Google Scholar]
- Martínez FC, Cansino AT, García MAA, Kalashnikov V, Rojas RL. 2014. Mathematical analysis for the optimization of a design in a facultative pond: indicator organism and organic matter. Math Probl Eng 1–12. [Google Scholar]
- Martinez SO. 2002. NIM-Azadirachta indica: natureza, usos múltiplose, produção. Londrina, PR: Instituto Agronômico do Paraná (IAPAR). [Google Scholar]
- Martins GB, Tarouco F, Rosa CE, Robaldo RB. 2017. The utilization of sodium bicarbonate, calcium carbonate or hydroxide in biofloc system: water quality, growth performance and oxidative stress of Nile tilapia (Oreochromis niloticus). Aquaculture 468: 10–17. [Google Scholar]
- Mirzakhani N, Ebrahimi E, Jalali SAH, Ekasari J. 2019. Growth performance, intestinal morphology and nonspecific immunity response of Nile tilapia (Oreochromis niloticus) fry cultured in biofloc systems with different carbon sources and input C:N ratios. Aquaculture 512: 734235. [Google Scholar]
- Montgomery DC. 2001. Design and Analysis of Experiments, 5th edn. New York: John Wiley & Sons Inc. p. 748. [Google Scholar]
- Mpeza P, Mavraganis T, Nathanailides C. 2013. Dispersal and variability of chemical and biological indices of aquaculture pollution in Igoumenitsa Bay (NW Greece). Annu Rev Res Biol 3: 873–880. [Google Scholar]
- Najdegerami EH, Bakhshi F, Lakani FB. 2016. Effects of biofloc on growth performance, digestive enzyme activities and liver histology of common carp (Cyprinus carpio L.) fingerlings in zero-water exchange system. Fish Physiol Biochem 42: 457–465. [Google Scholar]
- Pérez-Fuentes JA, Hernández-Vergara MP, Pérez-Rostro CI, Fogel I. 2016. C:N ratios affect nitrogen removal and production of Nile tilapia Oreochromis niloticus raised in a biofloc system under high density cultivation. Aquaculture 452: 247–251. [Google Scholar]
- Sarkhel C, Das SK. 2005. Impact of three piscicides on nitrogen-mineralizing and cellulose-decomposing bacterial populations. J Appl Aquacult 16: 167–182. [Google Scholar]
- Schneider O, Sereti V, Eding EH, Verreth JAJ. 2005. Analysis of nutrient flows in integrated intensive aquaculture systems. Aquac Eng 32: 379–401. [Google Scholar]
- Schryver DP, Crab R, Defoirdt T, Boon N, Verstraete W. 2008. The basics of bio-flocs technology: the added value for aquaculture. Aquaculture 277: 125–137. [Google Scholar]
- Subba-Rao NS. 1977. Soil Microorganisms and Plant Growth. New Delhi: Oxford and IBH Publishing Co. p. 289. [Google Scholar]
- Tavakol M, Arjmandi R, Shayeghi M, Monavari SM, Karbassi A. 2017. Determining multivariate analysis sampling frequency for monitoring contamination caused by trout farms. Polish J Environ Stud 26: 337–346. [Google Scholar]
- Vinaygam S, Dupare BU, Joshi OP. 2006. Traditional technologies in soybean cultivation in Madhya Pradesh. Indian J Trad Knowl 5: 25–33. [Google Scholar]
- Wei YF, Liao SA, Wang AL. 2016. The effect of different carbon sources on the nutritional composition, microbial community and structure of bioflocs. Aquaculture 465: 88–93. [Google Scholar]
- Wetzel RG, Likens GE. 1991. Limnological Analysis. 2nd Edition. New York: Springer–Verlag. p 391. [Google Scholar]
- Wu JT, Chou TL. 2003. Silicate as the limiting nutrient for phytoplankton in a subtropical eutrophic estuary of Taiwan. Estuar Coastal Shelf Sci 58: 155–162. [Google Scholar]
- Xie C, Li J, Li D, Shen Y, Gao Y, Zhang Z. 2018. Grass carp: the fish that feeds half of China. In: Gui JF, Tang Q, Li Z, Liu J, De Silva SS. (Eds.), Aquaculture in China: Success Stories and Modern Trends. John Wiley & Sons Ltd, 93–115. [Google Scholar]
- Xu WJ, Morris TC, Samocha TM. 2018. Effects of two commercial feeds for semi-intensive and hyper-intensive culture and four C/N ratios on water quality and performance of Litopenaeus vannamei juveniles at high density in biofloc-based, zero-exchange outdoor tanks. Aquaculture 490: 194–202. [Google Scholar]
- Xu WJ, Pan LQ, Zhao DH, Huang J. 2012. Preliminary investigation into the contribution of bioflocs on protein nutrition of Litopenaeus vannamei fed with different dietary protein levels in zero-water exchange culture tanks. Aquaculture 350: 147–153. [Google Scholar]
Cite this article as: Das SK, Mandal A. 2021. Supplementation of biofloc in carp (Cyprinus carpio var. Communis) culture as a potential tool of resource management in aquaculture. Aquat. Living Resour. 34: 20
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.