Research Article

Are hatchery-bred sandfish Holothuria scabra juveniles perceptive to potential food and predation?

¹ Aquaculture Department, Southeast Asian Fisheries Development Center, Tigbauan, Iloilo 5021, Philippines
² Institute of Marine Fisheries and Oceanology, College of Fisheries and Ocean Sciences, University of the Philippines Visayas, Miagao, Iloilo 5023, Philippines
³ College of Science and Mathematics, University of the Philippines in Mindanao, Tugbok, Davao City 8000, Philippines

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 7 February 2025
Accepted: 2 June 2026

Abstract

Restocking and mariculture of hatchery-bred sandfish Holothuria scabra are practiced in some countries to restore depleting wild populations and increase the global dried trepang or beche-de-mer supply. However, releasing cultured juveniles into the wild often results in slow growth and high predation mortalities, which may be related to their ontogenetic level of chemosensory ability to detect food and avoid predators. In a series of experiments using two-chambered aquaria, this study examined the preference responses (e.g., attraction, avoidance, or stationary) of hatchery-bred sandfish juveniles when presented with odors from predators (crab and fish), food (periphyton and formulated feed), combinations of odors, or the absence of odors (i.e., seawater only). Two groups were tested: small-sized sandfish (3–5 g, 4 months old) and medium-sized sandfish (15–20 g, 7 months old). Results showed that sandfish, overall, exhibited the lowest preference for predator odors, tending to remain stationary or select chambers either with seawater only or with food odors. When presented with conflicting predator and food odors, sandfish (particularly the small-sized group) showed a pronounced preference to be stationary, instead of being attracted to or avoiding any chemical odors. These results indicate that sandfish juveniles can detect and discriminate among chemical odors, with responsiveness and behavioral patterns varying across ontogenetic stages, sizes, and rearing histories. These findings provide essential insights that may improve husbandry protocols and optimize sandfish productivity in aquaculture or restocking operations.