Effects of Water Lettuce Pistia stratiotes Substitution on Growth and Health of Nile tilapia (Oreochromis niloticus)

This study aimed to assess the effects of substituting of Pistia stratiotes diets for soybean at 10 % (S10), 20 % (S20) and 30 % (S30) levels, and a control (S0) on Oreochromis niloticus. Three treatments and a control, each with triplicates, were used, with an initial weight and length of the fish being 15.5 g and 9.8 cm, respectively. A-90 day feeding trial was conducted. Proximate composition of the formulated isoproteic diets (30 % crude protein) was determined in the laboratory, while the fish were fed twice daily at 9 am and 5 pm. Weight and length were measured every two weeks, and at the end of the feeding trial, blood samples were collected to determine haematological and biochemical indices using standard analytical methods. The results showed that crude protein and fibre showed no significant difference except for S0 which varied from others in crude fibre (6.73±0.34). S0 recorded the best final weight, weight gain and protein intake, followed by S10 with significant differences. S30 recorded the highest red blood cells (6.12±0.41) and packed cell volume (40.0±3.20), while S10 (11.57±0.41) had the highest white blood cell count, AST (65.01±4.90), and total protein (68.10±2.30). The overall results revealed that 10% substitution of Pistia stratiotes for soybean, promoted growth and feed utilisation comparable to the conventional diets. However, the elevated values of WBC and AST in fish fed with Pistia stratiotes diets suggest potential threats to immune system and liver health of the fish.