Vitamin requirements of blue tilapias in a recirculating water system.
Fingerling blue tilapias (Tilapia aurea) were given vitamin-complete semipurified diets supplemented with different amounts of pantothenic acid or choline during 3 studies. A vitamin-free control diet was included in 1 study. Fish were kept in aquaria and supplied with recirculated water from a downflow gravel filter. There were no differences in weight gain, survival or feed utilization among fish in the different treatments, except for fish fed on the vitamin-free diet. Those fish became lethargic and anorexic, lost equilibrium, developed haemorrhagic areas in the skin and fins, and exhibited poor growth and low survival. It is suggested that tilapias could satisfy their requirement for pantothenic acid, choline, and possibly, other vitamins by feeding on bacteria in a recirculating system.