Toxic effects of the fish drug acriflavine on ampullary electroreceptors of catfish

Abstract

The fish anti-ectoparasite drug acriflavine proved to damage ampullary electroreceptor organs in the transparent catfish, Kryptopterus . We tested concentrations of 0.5-10 mg/l, and recorded both morphological changes and electrosensitivity in two types of experiments: short-term (2 h) with continuous monitoring and long-term (weeks) with occasional testing of receptor functioning. At the recommended therapeutical concentration (10 mg/l) and lower, the electrosensitivity is abolished within minutes to 0.5 h. The spontaneous spike rate is affected less. Recovery takes place at the lower concentrations only and even then is only partial (less organs, lower electrosensitivity). Most organs degenerated visibly in 1-3 days. Many receptors degenerated beyond recovery, leaving gaps in the original pattern. Some surviving organs have, after 15 weeks, a far too low electrosensitivity. The acriflavine is thought to damage the receptor cells rather than the nerve fibres.