Ontogeny and point-of-no-return of Amazon banded cichlid Heros severus larvae.

Abstract

This study describes the embryonic and larval development of the ornamental fish Heros severus, and the effects of delaying its initial feeding, providing insights for its captive breeding. Experiment 1 describes the embryonic and larval until hatching. The Experiment 2 determined the point-of-no-return (PNR) and evaluated the effect of delaying the first feeding on the development and survival of H. severus larvae. This experiment consisted of 10 treatments represented by the day of first feeding (delays of 1 to 10 days to first feeding), and two controls (positive: larvae continuously fed; negative: not-fed larvae. The cleavage occurred at 55 minutes post- fertilization and hatching at 53 hours post-fertilization at a water temperature of 28±0.5°C. The newly hatched larvae showed average total length of 4.18±0.18mm and remained attached to the substrate until mouth opening, which was observed at 125 hpf, when they filled the gas bladder and initiated swimming movements. The longer was the time for first feeding, the lower was larval weight and length. However, one day of feed deprivation did not affect larval development. The estimated point-of-no-return for H. severus larvae were 6 and 8 days for PNR50 and PNR100, respectively.