Effect of fishmeal replacement from Spirulina sp. and Lemna minor on growth and feed utilization of Red Tilapia (Oreochromis mossambicus)

Abstract

Searching for alternative ingredients to replace fishmeal from aquafeed is a crucial part in fish nutrition studies. An eight-week feeding experiment was conducted to evaluate the effect of fishmeal replacement with alternative ingredients such as Spirulina sp. and Lemna minor on growth performance, feed utilization efficiencies and stress resistance of red tilapia Oreochromis mossambicus. Three experimental diets were prepared by replacing 50% of fish meal in control diet by alternative ingredients as SD (10% of Spirulina sp.), LD (10% of Lemna minor) and MD (5% Spirulina sp. and 5% Lemna minor mix) and dietary effects of each feed were compared with control diet which contain 20% fishmeal (CD). Each treatment had three replicates. 180 fish (2.10±0.12 g) were distributed to 12 fiberglass tanks at an initial stocking density of 15 fish per tank. Tanks were randomly allotted to each treatment and fish were fed near satiety twice a day. Growth performance, survival rate, feed utilization efficiencies and stress resistance of the fish at the end of the experiment were compared with one way ANOVA. At the end of the experiment, 10 fish from each treatment were subjected to stress test (25 ppt). Results of this study show that the significantly highest body weights, mean feed intake, %Specific Growth Rate, %Average Daily Gain were observed from the diet of LD compared to CD. Feed Conversion Ratio were in the range between 1.06±0.00 to1.32±0.03 and it was highest in the LD. Higher salinity resistance was observed from the fish in SD followed by LD. 100% survival was observed from all treatments during experiment. Although there is no significant difference in moisture, ash, or protein content in fish flesh, lipid content of flesh in SD (2.53±0.00 %) was significantly higher that may occur due to higher absorption rate of Spirulina sp. rich with good fatty acid sources. This study concluded that the 50% of the fishmeal in CD diet can be replaced by Lemna minor as nutritious natural alternative low-cost ingredient without compromising growth, feed utilization and stress tolerance of red tilapia Oreochromis mossambicus.