Replacement effects of earthworm meal (Eisenia foetida) instead of fish meal on growth performance, feed efficiency, and survival rate of angelfish (Pterophyllum scalare)

In the present study, the dietary replacement effects of earthworm meal (Eisenia foetida) instead of fish meal were evaluated on growth, feeding performance, and survival rate of angelfish (Pterophyllum scalare). Fish (n=120; mean initial length and weight of 4 cm and 4.2 g, respectively) were distributed in four treatments (each with three replicates, totally in 12 aquariums) containing: fish meal diet (control), and three different inclusion levels of earthworm meal (10, 20, and 30%) instead of fish meal in a completely randomized design for 8 weeks. The results showed that the average daily growth rate and specific growth rate increased significantly with increasing the replacement level up to 20% but decreased at the level of 30% (p≤0.05). The best feed conversion ratio (FCR = 1.6) was recorded at the replacement level of 20% with a significant difference with other groups (FCR = 2.17-1.82) (p≤0.05). The average percentage of increase in body length at the replacement level of 20% was approximately 1.8 times that of the control group and the replacement level of 30% and 1.5 times the replacement level of 10%. Food efficiency values were in the range of 35-62%; and the highest value was observed at the replacement level of 20% (p≤0.05). Different levels of replacements had no effect on fish survival compared to the control group (p≥0.05). According to the results, a 20% replacement of E. foetida meal instead of fish meal in the diet improved growth and nutritional indices. Therefore, the use of earthworm meal at a rate of 20% is recommended in the functional diet of angelfish.