Four diets were developed in which equal weights of hydrolyzed feather meal (F) replaced equal weights of fish and meat and bone (FMB) meal in the following percentages: 0/100, 33/66, 66/33 and 100/0 (F/FMB). Each diet was proffered ab libitum to two replicate groups of 60 fry (mean wet weight 12·3 ± 0·3 mg) for 42 days. Survival was not significantly different among treatments (> 93%). The individuals fed 0/100, 33/66 and 66/33 (F/FMB) did not differ significantly in median or mean weight gain, however, individuals fed 100/0 (F/FMB) were significantly smaller than those fed all other diets at days 21 and 42. The growth of Oreochromis niloticus fry was not compromised by replacement of up to 66% of fish meal and meat and bone meal (9·9% of the total diet) with feather meal. Feeding feather meal as a sole source of animal protein, however, appears to result in a decrease in weight gain and associated growth parameters. © 1996.