Early development and point of no return in starvation of Betta splendens larvae

In order to investigate the effects of starvation on the early growth and development of Betta splendens larvae, a starvation stress experiment was conducted to analyze yolk sac absorption, growth, development, and initial feeding rate. The results showed that newly hatched larvae were in the endotrophic stage from 0 to 2 days post-hatch (dph), the mixed feeding stage from 2 to 4 dph, and the exogenous feeding stage from 4 dph onwards. The growth rate of larvae was higher from 0 to 2 dph, with no significant difference between the fed and starved groups at 3 dph. However, significant differences appeared after 4 dph. Growth inhibition was observed in the starved group from 5 dph, with evident growth stagnation at 8 dph, whereas the fed group continued to grow well. The initial feeding rate of larvae was (23.33±5.77)% at 2 dph, reached 100% at 3–5 dph, and declined after 6 dph. The Point of No Return (PNR) occurred between 7 and 8 dph. The optimal initial feeding time for larvae is 3 dph, and feeding should commence no later than 7 dph.