An energy budget for an omnivorous cyprinid: Rutilus rutilus (L.)

Two to three year old roach (9–15 g body weight) were fed ad libitum with grass or with meal worms. After three weeks, both groups of fish showed a positive energy budget. However, with a grass diet, production was low (only 7% of that of meal worm feeding fish) with an increased of lipids, whereas the protein content of the body decreased. Non-crude fiber organic matter of grass was utilized to 47.6%, that of meal worms to 82.4%.