In this study, the effect of commercial food replacement with earthworm (Eisenia foetida) on growth, survival, the number of larvae and their resistance to larvael salinity stress in Swordtail fish (Xiphophorus helleri) was investigated. A completely randomized design experiment comprising of four treatments: T1 (100% commercial food), T2 (25% Earth worm +75% Commercial food), T3 (50% Earth worm + 50% commercial food), T4 (75% Earth worm + 25% Commercial food) were performed in triplicate. Swordtail fish were fed with 3% biomass and 3 times per day. After a 60-day experimental feeding period, growth factors and survival rate of fish fed with different diet treatments were not affected. However, the growth factors and survival were affected by sex and the weight gain, specific growth rate and survival rate of females was significantly higher than males. The highest number of born larvae was observed in T2 which was significantly more than control. (p<0.05). In T4, larvae showed the lowest resistance to salinity stress test (p<0.05). Results showed that number of born larvae significantly increased in 25% replacement than control, so the Swordtail fish could be fed with low levels (25%) of earthworm without any unfavorable effects on the growth and survival rate and their larval resistance to salinity stress test.