Effect of increasing vitamin B3 in a combined Nile Tilapia (Oreochromis niloticus) and lettuce (Lactuca sativa), and a functional study of plant and fish growth indices

In order to investigate the effect of dietary-vitamin on growth and immunity indices in Nile tilapia (Oreochromis niloticus) and lettuce (Lactuca sativa) in an aquaponics system, 240 tilapia pieces with the average weight of 12 ± 1.25g and 240 seedlings of lettuce were randomly introduced into nine experimental unites. The treatments were different rates of vitamin B3 concentration in the fish feed with the levels of 20, 40 and 60 mg per kg. Growth indices did not show any significant difference among treatments (P≥0.05). Lettuce growth indices such as final leaf length and final leaf width showed a significant difference among treatments (P <0.05). The plant final height, plant fresh weight, plant dry weight, root fresh weight and dry weight were not significantly different (P≥0.05). Biochemical parameters of blood in fish showed the highest mean concentration of total protein, glucose and triglyceride levels in treatment with 60 mg of vitamin per kg compared to other treatments (P <0.05) , however blood indices such as serum cortisol, alkaline phosphatase and aspartate aminotransferase contents were not significantly different (P≥0.05). It was concluded that, with increasing the vitamin B3 at the rates of 40 to 60 mg in feed, can improve tolerance of fish to stress and increase the fish growth and lettuce in the culture system.