Protein nutrition of farmed tilapia: searching for unconventional sources

Tilapia are the third most important cultured fish group in the world, after carps and Salmonids. Tilapia culture is also one of the fastest growing farming activities, with an average annual growth rate of 13.4% during 1970–2002. They are widely cultured in about 100 countries in the tropical and subtropical regions. As a result, the production of farmed tilapia has increased from 383,654 mt in 1990 to 1,505,804 mt in 2002, representing about 6% of total farmed finfish in 2002. Feeding represents over 50% of the operational costs of aquaculture. Fish meal has been widely used as a main conventional protein source in aquafeeds. However, the dependence on fish meal is expected to decline due to the shortage in world production of fish meal, and increased demand for fish meal in feeds for livestock and poultry industries. Therefore, partial or total replacement of fish meal with less expensive, locally available protein sources will become inevitable. Many attempts have been conducted alongside this line. The present review throws the light on alternative dietary protein sources for farmed tilapia, with emphasis on the most cost effective, commonly used sources, such as fishery by-products, terrestrial animal by-products, oilseed plants, aquatic plants, single cell proteins, grain legumes, plant protein concentrates and cereal by-products. The nutritive values, inclusion levels, constraints and economic evaluation of these sources are discussed.