Nutrient and energy content of freshwater fishes

The analyses of fresh total body homogenates of 2385 freshwater fishes from 17 species originating in natural waters and aquaculture facilities resulted in average values of 19.1–37.8% dry matter, 13.6–18.3% crude protein, 0.8–18.3% crude fat, 0.16–2.17% nitrogen-free extracts (NFE), 2.2–2.9% nitrogen and 0.39–1.02% phosphorus. The gross energy content ranged from 3.83 to 11.49 MJ/kg. With increasing fat content in the fishes, water content decreased and dry matter content increased. Through this interdependence, a significant correlation was found between dry matter and crude fat and energy content (r2=0.92–0.97). The values of crude protein, crude ash, NFE, nitrogen and phosphorus did not show any significant influence on dry matter content (r2=0.0005–0.46). Based on the significant correlation between dry matter and gross energy (gross energy [MJ/kg]=0.0253 dry matter [%]1.6783), the energy content of freshwater fishes can easily be estimated by the dry matter content in the total body.