The influence of feeding reduction on the survival and growth of the larvae and postlarvae of freshwater prawn (Macrobrachium rosenbergii): an applied biofloc technology study

This study involves a research conducted in hatcheries concerning the impact of feed reduction on the survival, productivity and growth of the larvae and postlarvae (PL) of freshwater prawn (Macrobrachium rosenbergii). The experiment included cohorts with different daily feeding schedules, i.e., (i) Artemia twice + artificial feed thrice (control); (ii) Artemia twice + artificial feed twice; (iii) Artemia twice + artificial feed once; (iv) Artemia once + artificial feed thrice; (v) Artemia once + artificial feed twice; (vi) Artemia once + artificial feed once. Refined sugar was supplied as a carbon source to create biofloc from larval stage-4, and the C/N ratio was maintained at 17.5. A 250-L tank was used for larval rearing, stocking density was 60 ind L-1, and salinity of 12%o. The results obtained imply that environmental factors, bacterial factors, and biofloc parameters were in a suitable range for PL to develop; the greatest PL15 length (10.03±0.51 mm) followed treatment (i), with significant differences (p < 0.05) observed for treatments (v) and (vi) but no significant differences (p > 0.05) observed for any of the remaining treatments. The highest survival rate and productivity were observed for PL15 under treatment (i) (56.8% and 27±1.05 ind L-1 respectively); although no significant differences (p > 0.05) were observed for treatment (ii), significant differences (p < 0.05) were observed for the remaining treatments. Towards the end of the experiment, the feeding regime was modified by removing one artificial feed instance; this did not negatively impact growth, survival, or productivity compared to the conventional feeding regime.