Optimum density ensures sustainable aquaculture providing proper utilization of feed, maximum production, sound environment and health of all aquatic species. The main objective of this study was to compare Nile tilapia (Oreochromis niloticus) performance at different stocking densities and recommend the ‘golden’ stocking density in earthen ponds.
An experimental study was conducted to analyse survival rate, growth, harvest yield and fish welfare, from which nine square earthen ponds (each of 2500m2) were used representing 3 treatments. SD1, SD2 and SD3 being 8, 16 and 24 fish/m2 respectively and each treatment was triplicated. Fish were fed floating feed and aeration was supplied to the earthen ponds with a 5% water exchange every second day. Water quality parameters (ammonia, pH, Temperature, Dissolved oxygen and turbidity) were monitored weekly, and sample weighing was conducted fortnightly to assess fish growth.
From the replications conducted, SD3 (24 fish/m2) had the lowest survival rate averaging 72% compared to SD1 and SD2 recording 100% and 97% respectively. SD1 had a higher daily gram intake (G.I) and higher average body weight (ABW) than SD2 and SD3 recording 1.87-336g, 1.36-244g and 0.88-158g respectively. The most biomass per volume was realized in SD2 averaging 2.54kg/m3 followed by to SD3 and SD1 recording 1.87kg/m3 and 1.81kg/m3 respectively.
In conclusion it is observed that higher stocking densities does not equate to higher production as overstocking will have a negative impact on growth and survival rates in the cultivation of Oreochromis niloticus. Lower stocking densities however may result in better fish growth as seen in SD1 (8fish/m2) which may be preferred by farmers targeting bigger fish sizes. For farmers targeting to maximize production (biomass per volume or area) SD2 (16/m2) is the ‘optimal middle grounded choice that strikes a balance between cost and benefit compared to the other two treatments.
Key words: Production, Optimum, Oreochromis niloticus, Stocking density, Biomass, Earthen ponds