Biofloc technology positively affects Nile tilapia (Oreochromis niloticus) larvae performance

• The effect of producing and culturing Nile tilapia larvae in biofloc technology based systems is investigated.
• Maintaining broodstock in a biofloc system increased tilapia larval survival and tolerance to salinity stress.
• Housing broodstock and larvae in a biofloc system increased tilapia fry resistance to Streptococcus agalactiae infection

The effect of producing and culturing Nile tilapia (Oreochromis niloticus) larvae in biofloc technology (BFT) based systems was investigated in terms of larval growth performance and robustness. Broodstock fish were maintained in a system with and a system without the application of biofloc technology in order to produce larvae. Molasses (53% C) was added daily into the biofloc system at an estimated C/N ratio of 10. A growth test was performed with larvae that were harvested from the biofloc system and the control system and that were subsequently housed in a biofloc environment or a control environment according to a 2 × 2 factorial design. The survival of the larvae from BFT origin (90–98%) was higher than the survival of the larvae from control origin (67–75%). The growth performance of the larvae did not seem to be affected by the origin or the housing of the larvae, although the growth seemed to be more uniform when the larvae were housed in BFT water. Upon infection with the pathogenic bacterium Streptococcus agalactiae, the larvae from BFT origin showed a significantly higher survival (75–80%) than the control larvae housed in control water (ca. 55%). Housing of the control larvae in BFT water resulted in an increase in infection resistance (about 70% survival). In a salinity stress test, the tolerance of the larvae to osmotic stress at 35 g/L for 1 h was assessed. The larvae of BFT origin showed a survival of 72% and 42% at 1 h and 24 h post salinity stress, respectively. This was significantly higher than for the larvae of control origin that showed a survival of 33% and 5% at these respective time points. Overall, the data show that the application of biofloc technology for tilapia brood fish maintenance and larval production can improve Nile tilapia fry quality and production performance.