Effects of stocking density on growth and survival of young Gulf killifish in recirculating aquaculture systems

Gulf killifish, Fundulus grandis, is a hardy marine baitfish with established rearing techniques in ponds and static pools, but there is little information about the use of recirculating aquaculture systems (RAS) for growing killifish.The current trial investigated the effects of stocking density on growth and survival of young killifish in RAS. Young fish (28-day posthatch) of 51.6 ± 0.9 mg (mean ± SE) were stocked at 2, 5, 8, and 11 fish/L in 31 L tanks in RAS with triplicate groups for 16 weeks. Cannibalism was a major problem in the study, which increased with increasing initial stocking density, affecting survival negatively. Survival decreased (P < 0.03) with increasing initial stocking density and culture period. At the end of the trial, the 2, 5, 8 and 11 fish/L initial stocking density reduced to 1.66, 1.42, 0.86, and 0.74 fish/L respectively. A significant linear relationship existed between the initial stocking density and weight (y = 0.077x + 2.3; R² = 0.8; P = 0.003), whereas an inverse relationship occurred between initial stocking density and survival parameters (y = −9.43x + 97.4; R² = 0.89; P < 0.001). From the trial, the optimum density for culturing young of Gulf killifish in RAS appears to be around two fish/L.