Responses of the electric fish Gnathonemus tamandua (family mormyridae) to changes in ph

Abstract

The response of the tropical mormyrid fish, Gnathonemus tamandua, to variations in pH (within a range of 4.5 to 9.0) at a constant temperature of 27.5°C ± 0.5°C has been evaluated. Fluctuations in electric organ discharge (EOD) were detected using plate electrodes and a microcomputer produced counts as pulses per minute (PPM). The introduction of alkaline conditions (up to pH 9.0) significantly increased the rate of EOD while acidity (down to pH 4.5) acted to reduce it. The optimum pH for stable pulsing was established at 7.1.

Keywords:

• Electric organ activity
• Gnathonemus
• pH