Lack of a sustainable protein supplement for use in fish feed formulation is a challenge to the aquaculturalists in the 21st century that necessitates identification and testing of conventional sources. This research aimed at determining the potential of earthworm as an alternative protein source in fish feed. A six-week feeding trial was conducted to assess the growth and survival rate of the Nile tilapia (Oreochromis niloticus) fry fed on earthworm meal as protein supplement. Diets containing 0% (D0), 25%(D25), 50%(D50) and 100%(D100) replacements of fish meal with earthworm meal were formulated. All diets were isonitrogenous (54%) and fed thrice daily to triplicate groups of O. niloticus fry at 3% body weight. Diet D25 had a significant effect on growth of and feed utilization (p= 0.002) by O. niloticus. Final weight, weight gain, daily weight gain, and specific growth rate, were also highest in fish fed diets D25. A similar growth pattern was observed for length measurements. Fish fed diets exceeding 25% replacement of fish meal with earthworm meal had depressed growth. It is concluded that fish meal can be substituted with earthworm up to 25% in the diet of O. niloticus without adverse effect on growth and feed utilization.

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