Understanding Fish Larvae’s Feeding Biology to Improve Aquaculture Feeding Protocols

Abstract

Knowing that food ingestion and digestion are processes under neuroendocrine regulation, it is important to understand how fish larvae regulate these processes, when the digestive system itself is under development. This study aimed to analyze how gilthead seabream (Sparus aurata) larval feeding incidence and intensity were affected by time, light, and water temperature, through the analysis of gut content and how this affected cholecystokinin (CCK) content. Three short-term experiments were done: (A) 27 and 42 days post-hatch (DPH) larvae were analyzed at different intervals for 80 min, after feeding; (B) 38 and 48 DPH larvae were kept under different light intensities (0, 400, 1000 lux) for 30 min; (C) 41 DPH larvae were kept at 17, 19, 25 °C for 30 min. Feeding incidence below 100% was observed for 27 DPH larvae, and for 38 DPH larvae fed at 0 lux. Feeding intensity was several fold higher at older ages. However, the number of prey in the gut was lower at 0 lux, and higher at 25 °C. Overall, no clear pattern was observed for CCK, but at older ages increasing gut content resulted in higher CCK content. In conclusion, until 38 DPH light is important for gilthead sea bream larval feeding ability, and maturing functionality of CCK was only observed at later stages.