Association of Oxytetracycline and Florfenicol affects zebrafish larvae behavioral repertoire

The fish farms are increasingly growing and, consequently, the use of antibiotics in aquaculture. Oxytetracycline (OTC) and Florfenicol (FF) are the most common antibiotics applied in the fish production sector and livestock farming. The elucidation of the effects of the antibiotics is essential to control their use and their physiological and pharmacological implications. Here we studied the behavioral effects of the 96 h-exposure to OTC (2, 10, 20, and 100 mg/L), FF (0.01, 0.05, 2 and 10 mg/L) or OTC (10 mg/L) + FF (10 mg/L) in zebrafish larvae. We observed that the covered distance and the movement increased in animals exposed to OTC + FF when compared to control. In addition, fish entered the center of the plate test more often and stayed there longer. The turn angle was reduced at OTC + FF. We also observed that the optomotor response was compromised by 10 and 20 mg/L OTC and to OTC + FF. Our data demonstrated that there is an increase in the number of entries in the center area and time spent in center area for FF- and OTC + FF-treated groups. These data showed that the antibiotics promoted a reduction of anxiety-like behavior allowing larvae to explore more the novel environment as well as a detrimental performance for the optomotor response. Highlights Florfenicol (FF) did not alter exploratory and anxiety-like behavior in zebrafish larvae. Oxytetracycline (OTC) did not alter exploratory behavior, but there was an increase in the time spent in the center area OTC plus FF increased distance and movement in zebrafish larvae. OTC plus FF reduced the anxiety-like behavior in zebrafish larvae. Optomotor behavior was compromised by treatments with OTC or OTC + FF.