Replacement of Fish Meal with Graded Levels of Earthworm Meal in the Diet of Fingerlings： Effect on Feed and Growth Parameters

The study was aimed at evaluating growth response of Heteroclarias fingerlings fed diet in which fish meal was substituted with graded levels of earthworm meal. The replacement levels were 0.00%, 25%, 50%, 75% and 100% designated as E0, E25, E50, E75 and E100, respectively. Fingerlings used for the work were obtained through artificial insemination of brood stock (purchased from local farmers) with ovaprim in the laboratory. The resulting fry were reared and fed with cultured plankton for 2 weeks followed by 100% fish meal for another two weeks. Thereafter sixteen fingerlings weighing 4.73 g and measuring 6.512 mm standard length (on the average) were starved over night and reared in five indoors tanks (0.8 × 0.5 × 0.5 m) in duplicate for eight weeks. Fingerlings were fed on graded earthworm meals of 40% protein twice daily at 08:00 and 16:00. The highest mean weight (6.77 g), specific growth rate (0.86) and protein efficiency ratio (0.6) were obtained at 50% replacement level. Also, Food conversion ratio was the highest at 50% substitution level and lowest at 0.00% substitution, indicating that fingerlings use earthworm containing meal more efficiently. Furthermore, cost benefit analysis revealed that the profit index for 50% inclusion of earthworm meal was the highest (1.71) and the highest net profit of N374.32 (circa $2.3) was achieved at this level. Water quality parameters observed were within tolerable values for the fingerlings well being. Consequently, farmers are advised to use 50% earthworm meal in place of fish meal for formulation of Heteroclarias fingerlings diet. This will drastically reduce production cost, increase farmers profit and enhance the biological value of our menu.