Effect of water temperature and food availability on growth performance, sex ratio and gonadal development in juvenile convict cichlid (Amatitlania nigrofasciata)

Temperature and food availability are key drivers of growth and reproductive development in fishes, but information on how they interact is poorly understood. This study investigates the effects of water temperature and food availability on growth, sex ratio and gonadal development of the convict cichlid (Amatitlania nigrofasciata) which is an ornamental fish that may be a useful lab model. For this experiment, 180 juvenile convict cichlid (0.3 ± 0.02 g) were held at three different temperatures (26, 29 and 32 °C as T1, T2 and T3) and fed to satiation (S) or a restricted diet (R: half satiation) during a 56-day experimental period. Specific growth rate was significantly higher in T2S treatment than the other groups. The highest and lowest mean oocyte sizes were recorded in T1S and T3R groups, respectively. The sex ratio of fish held at 29 °C was male biased (female, 21.0%; male, 78.9%), but this was not seen at 26 °C (female, 47.6%; male, 52.4%) or 32 °C (female, 57.1%; male, 42.9%). In T1S and T1R treatments, oocytes developed more than the other treatments and in T2S group testicular development was more advanced than other groups. These results demonstrate the complex interplay of temperature and food availability on growth and reproductive development in the convict cichlid. Appropriate food availability significantly improves growth and reproductive processes, while restricted feeding decreases growth, survival rate and reproductive performance.