Uneaten Feed Quantification in Fish Farming Growing Phase of Dicentrarchus labrax, Feeding Flow and Distribution Modes Effects

The economic and environmental sustainability of fish farms depends on the improvement of farming practices. Considering the fish feed high cost and environmental impacts, fish farmers continually need to improve feed efficiency, essentially through good feeding practices. Reduction of uneaten feed is an unavoidable objective for fish farmers to achieve this goal. This study aimed to improve the feeding practices and highlight the effects of slowing feed distribution flow rate on uneaten feed rate (Ruf) in caged sea bass (Dicentrarchus labrax) under continuous and discontinuous feed distribution modes in the commercial aquaculture farming conditions of M’diq Bay, Moroccan Mediterranean. A conical polyamide net was placed in the external, surrounding position of the entire experimental cage to ensure capturing all uneaten feed. Collected wet feed pellets were dried and weighed to quantify uneaten feed; three repetitions were performed during each experiment for each feed distribution mode and flow rate. Results showed that uneaten feed quantity (Q_df) was higher in manual discontinuous distribution mode at a fast flow rate of 20 kg/min. Slowing down the fish feeding flow rate from 20 to 10 kg/min reduced the uneaten feed rate from 3.7 to 0.2%. Similar findings were observed for continuous pneumatic fish feed distribution mode where rate decreased from 0.8 to 0.02%. Significant statistical differences between the two fish feed distribution modes and between the two experienced fish feeding flow rates were observed. The further high positive impact of slow and continuous fish feeding flow was recorded on feed efficiency in sea bass farming.