INTESTINAL HISTOLOGY AND ENTEROCYTES HEIGHT VARIATION IN RAINBOW TROUT (Oncorhynchus mykiss) GROWN IN CAGES: EFFECTS OF ENVIRONMENTAL CONDITIONS

Rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) was grown in cages (water reservoirs "Bocac", Bosnia and Herzegovina) in two separate experiments for a period of 90 days (autumn - winter and spring - summer). Trout were fed six different feed formulations and studied their influence on rainbow trout intestine histology. Normal histological structure of this part of the digestive system was found. The results showed that with water temperature and feed quantity decrease, the height of enterocytes increases; while with increase of water temperature and amount of food given to the fish, the average height of enterocytes decreased.