Duplicate groups of Tilapia zillii fry reared in ten aquaria were fed one of isonitrogenously five different diets for 90 days. Formulated con­trol diet containing 20% crude protein was used. A whole part of the diet was replaced with either 0, 25, 50, 75 or 100% Azolla pinnata meal. Results showed growth retardation of the fish proportional to the in­creasing Azolla level in the diet. Mortality rate reached 23% for fish fed 100% Azolla meal. Carcass composition showed increased moisture and ash contents and poorer content of CP and EE. Values of feed conver­sion ratios were higher; PER, PPV% and EU% were lower with increasing Azolla level. Azolla is not nutritionally efficient for T.zillii fry at high inclu­sion levels. However, levels below 25% may be promising as an ingredi­ent in fish feed in view of being costless protein source.