Comparison of Taste Reception and Feeding Behavior of the Nile Tilapia Oreochromis niloticus (Cichlidae) of Different Age

Abstract

Comparison of specimens of the Nile tilapia Oreochromis niloticus of two age groups did not show any significant differences. L-cysteine, L-lysine and citric acid have an attractive taste for juveniles (age 1.5 months, body length 6.5–7.0 cm, weight 5–7 g); L-cysteine and citric acid have an attractive taste for adult fish (4 months, 12–15 cm, 45–50 g). The other eight L-amino acids have an indifferent taste for fish of both age groups. Based on the data obtained and the results of other studies, a hypothetical scheme is proposed, according to which the fastest functional transformations of taste reception in fish ontogeny occur after the start of exogenous feeding of larvae and are completed before maturation. Fish of both age groups rarely re–grasp pellets flavored with taste substances, but juveniles spend much more time on pellets orosensory evaluation, up to 1.4–1.6 times. Regardless of the fish age, such an assessment requires more time if the testing of pellets ends with their ingestion. The differences may indicate an undeveloped stereotype of feeding behavior in juveniles of Nile tilapia.