This experiment was carried out to evaluate the effect of earthworm (Eisenia fetida) in diet for Oscar fish (Astronotus ocellatus) in a randomized design with three treatments in triplicates using 9 aquarium for 9 weeks. Twenty pieces of Oscar fish with average weight 3.6±0.5 g were stocked in each replication. The earthworm meal (as fed) at the levels of 0, 50 and 100% was replaced with Biomar diet in Oscar fish diet. Fish were fed with experiential diets included: 1-Biomar 2- Mixture of Biomar and earthworm meal with equal ratio 3- Earthworm meal. Daily food intake calculated by the weight of fish (3% of body weight) and fish were fed 3 times a day. Physical and chemical properties of water, such as temperature (28.2°C±0.5), oxygen (7.8ppm±0.2) and pH (8.1±0.11), were control.  At the end of study growth performance, feed utility and survival rates were measured. The highest body weight increase (173.2% (gr)±0.23), specific growth rate (2.02 (%)±0.26), average daily growth (17.4 (%)±3.15), protein efficiency ratio (1.85 (%)±0.16) and least feed conversion ratio (0.99 (%)±0.05) observed in Biomar treatment (p<0.05). But greatest survival ratio observed in diet contained earthworm powder. The results assessment showed that neither 50% nor 100% worm meal could not supply Oscar fish nutritional requirements.