Effects of different levels of Sargassum ilisifulium extract on growth performance and some skin mucosal immunity of red tilapia (Oreochromis mossambicus × Oreochromis niloticus)

Improving the immune system and growth of fish with seaweed instead of antibiotics can be a good idea for aquaculture. For this purpose, twenty four hundred red tilapia fish after adaptation to laboratory conditions were divided into four treatments with three replicates, and then fed diets contained control (without sargassum extract), 1, 2, and 3% of Sargassum ilisifulium extract for 8 weeks. The results showed that 2% Sargassum extract causes a significant increase in growth indices (specific growth factor, weight gain) and a significant decrease in food conversion ratio (P<0.05). All fish fed with different levels of Sargassum extract had more protein and less fat contents in the body compared to the control group (P<0.05). The amount of total protein, immunoglobulin, and lysozyme activity of the mucus in the fish fed with 2% Sargarsum extract was significantly higher than other experimental groups. (P<0.05). As a result, it is suggested to use 2% of dietary Sargassum extract to improve immunity and growth performance of red tilapia fish.