Bait composition, feeding frequency, stocking density, and water quality for the effective cultivation of large-sized redclaw crayfish seedlings

To achieve better large-sized seedling cultivation, the effects of bait composition, feeding frequency, stocking density, and water quality on effective cultivation were examined. For experiment 1, newly hatched juveniles were cultivated for nine days in a cement pool greenhouse and screened for suitable bait composition and feeding frequency. Groups 1, 2, and 3 were fed once, twice, and thrice a day for formulated feed, group 4, 5, and 6 were fed once, twice, and thrice a day for 80% formulated feed+10% Spirulina powder+10% Antarctic krill oil. Survival and growth rates of juveniles were examined. For experiment 2, temporarily reared juveniles were selected as seedlings in a pond greenhouse. The survival rate of juveniles at different densities after two months was calculated, and the changes in plankton and water quality were analyzed. Experiment 1 revealed that the survival rates, final weights and total lengths of Groups 6 and 5 (fed twice and thrice a day for formulated feed adding Spirulina powder and Antarctic krill oil) were significantly higher than those of Groups 1 and 2 (fed once and twice a day for formulated feed). Experiment 2 showed that the survival rate of Zones 1-1 and 1-2 (Density = 20000 tails/acre), 2-1 and 2-2 (15000 tails/acre), and 3-1 and 3-2 (10000 tails/acre) was 48.43 ± 2.23%, 53.26 ± 3.14%, and 58.86 ± 3.48%, respectively. The survival rate in the 10000 tail/acre group was significantly higher than that in the 20000 tail/acre group. During seedling cultivation in a pond greenhouse, the ammonia nitrogen and nitrite reached a maximum of 1.6 and 0.317 mg/L, the pH fluctuated between 7.08 and 9.91. The plankton population was relatively abundant, and Cyanobacteria grew in large numbers. In short, 80% feed+10% Spirulina powder+10% Antarctic krill oil was fed thrice or twice a day as bait composition and feeding frequency helped improve the survival and growth rates of juveniles. Density of 10000 tail/acre in pond greenhouse improved the survival rate of juveniles. In addition, regular testing is required to ensure the suitability of the environment and improve the effectiveness of seedling cultivation in pond greenhouses.