The present study was conducted to compare the utilization of several different carbohydrate sources and to evaluate the effect of two different methods of feed-processing in eel feeding. Five experimental isoenergetic diets were formulated (all containing 28.5% protein, 8% fat and 40% carbohydrate in dry matter), differing in the carbohydrate source: raw wheat starch (RWS diet), corn malto-dextrins (MD diet), manioc ( Manihot dulcis) meal (MAN diet) and pregelatinized corn starch (PCS1 diet). These four diets were manufactured by extrusion in a Clextral BC-45 extruder. A fifth diet was prepared with the same pregelatinized corn starch (PCS2 diet) but by using a customary laboratory procedure: pellets were made in a mincing machine after mixing dry premix with water and thereafter dried under hot-air flow. Each experimental diet was supplied to three lots of European eels. Feed acceptance, growth, feed efficiency, digestibility, dietary protein utilization, and effects on body composition were evaluated. All extruded diets were well utilized and promoted similar growth rates, irrespective of the origin and nature of the carbohydrate source. Diet PCS1 resulted in more tough pellets and was poorly accepted by the eels; besides its digestibility was clearly lower, so growth rate and feed conversion were the poorest. Results confirm the ability of eels to use high dietary carbohydrate levels and demonstrated the importance of selecting an appropriate processing method when these high carbohydrate levels are to be utilized.