Zootechnical and reproductive performance of juvenile male Astyanax lacustris (Yellowtail Lambari) cultivated in Biofloc Technology (BFT) and Recirculating Aquaculture System (RAS).

A total of 1600 juvenile Astyanax lacustris (commonly known as yellowtail lambari) with an initial age of two months were used. Fish were subjected to two systems: biofloc technology (BFT) and clear water recirculation (RAS) in a completely randomized design. Replicates were established for each treatment, and carbon sources and carbon ratios were adjusted specifically for BFT tanks to optimize microbial floc formation. Feeding was based on 3% of the total biomass of each tank, which was reduced to 1% when the fish reached four months of age. The gonadal factor and gonadosomatic index (IGS) were superior in fish cultured in the RAS system during the third month of culture, although all gonads from both BFT and RAS systems showed reproductive capability based on histological analysis. The hepatosomatic index (IHS) was higher in the BFT system in the third month. BFT males exhibited a higher percentage of dry matter and ether extract in body composition, while RAS males had a higher percentage of crude protein and ash. At five months, RAS males displayed superior total progressive motility, rapid sperm count, and flagellar beat frequency compared to BFT males. By fourteen months, RAS males had sperm with higher total motility, VSL (curvilinear velocity), VSL (linear velocity), and VAP (average trajectory velocity) than BFT males. Based on these results, BFT proves effective for the general cultivation and reproductive maintenance of Astyanax lacustris, although RAS offers slight advantages in seminal quality for male fish.