About a decade and a half ago, Nile tilapia was majorly (about 80%) raised in earthen ponds. However, due to the poor nutrient recycling in fishponds leading to poor water quality, coupled with other factors such as fish diseases, causing fish mortalities, poor fish yields and heavy financial losses, many farmers are abandoning the ponds and leaving the business. The nutrients of concern are nitrogen(N), phosphorus (P), and carbon(C) from the highly nitrogenous waste feed materials. Water exchange, the commonly practiced water quality control measure, is being constrained by water supply shortage in the Agro-ecological zones throughout the production cycle. Recent studies have demonstrated a potential water saving control method which involves use of high carbon to nitrogen (C/N) diets with the dietary carbon sourced from the high profile insoluble-NSPs products such as Baggase, rice bran etc. The diets being low in nitrogen, lowers the level of nitrogenous wastes, and increases the pond C/N levels. An increase in pond C/N ratio above 10, promotes the growth of specific live food organisms that utilize the pond organic wastes improving pond water quality, and reducing the need for water exchange. In this study therefore, we will test the effect of dietary C:N:P ratios in tilapia-formulated feeds by exploring the use of the locally available NSP-rich food stuffs on pond productivity, water quality and fish production.
Methods: Four test diets having two test NSP-products combinations e.g., i). Baggase, Palm oil kernel, sunflower seed cake, and ii). Baggase, Coffee husks, Rice bran, at two C/N ratio i.e., (i.e., <10, and >10) will be formulated and used, with the standard commercial tilapia diet (C/N = 8) as the control diet. All-male juvenile Nile tilapia will be used. The trial will be conducted in 15 hapas of 20 m3 (5 x 4 x 1 m) fixed in five 200 m2 ponds. A cost benefit analysis will be conducted to determine economic benefits.
Expected Results: NSPs composition of the locally available plant material determined and profiled. Best performing NSPs food-stuff (s) identified. A suitable cost-effective diet(s) (i.e., dietary C:N:P ratio(s)), that best promote pond nutrient recycling, improving water quality, N. tilapia yields, and profitability determined.
Conclusions: The project is expected to improve on pond nutrient recycling by promoting growth of specific live food organisms that utilize the pond nutrients, promoting good pond water quality, and Nile tilapia production.
Keywords: Non-starch Polysaccharides, Carbon to nitrogen to phosphorous (C:N:P).