The purpose of the study was to examine how various protein compositions affected the digestibilities and retention of nutrients during eel farming in controlled tanks. The average size of the eel fish samples used was 70± 1.53g/ ind. This study used a completely randomized design with four treatments and three replications. The protein content of treatment A's feed was 35%, treatment B's was 40%, treatment C's was 45%, and treatment D's was 50%. The variables that were observed included water quality, protein and fat retention, in addition to the digestibility of proteins and their overall composition. The W-Tukey Test and analysis of variance were employed in the data analysis. The feed treated with 50% protein content, or 92.01%, had the maximum protein digestibility, according to the data. The feed with a protein content of 35 and 50% had the highest level of feed digestibility of fat, which was 89.37. Additionally, the highest values of nutrition retention and extract components without nitrogen digestibilities were found in feed with 50% protein content, respectively, at 81.31 and 26.54%. In addition, the feed recorded the highest fat retention and a protein level of 14.37 at 45%. In general, every treatment used throughout the study fell within the range of water quality that is appropriate for eel fish growth and survival.