Responses of electric fish (family mormyridae) to inorganic nutrients and triubinryltin oxide

A microcomputer-based fish monitor has been used to evaluate the effect of selected inorganic nutrients and Tributyltin Oxide (TBTO) on the electric organ discharge (EOD) of two species of elephant fish, namely Gnathonemus petersi and G. tamandua (family: Mormyridae). Significant EOD responses to dosing concentrations as low as 1.0mg/l ammonia (NH4-N), 0.05mg/l phosphate (PO4-P) and 0.01mg/l TBTO are recorded by both species, with response times within a 15–45 minute range. No response, however, was recorded to concentrations within a range of 10–75mg/l Nitrate (NO3-N). This should reduce the instance of ‘false alarmsʹ for which such systems are renowned. These findings add further credibility to the potential of these fish for use as indicators of chemical changes in water quality.