Apomorphine and haloperidol influence electric behaviour of a mormyrid fish.

The electric behaviour of the mormyrid Gnathonemus petersii is changed by dopaminergic drugs applied to the aquarium water. The upper limit of the interpuls interval distributions is significantly shifted to shorter intervals by apomorphine-HCl (.082 - .328 mg/ml), and to longer intervals by haloperidol (.041 - .164 mg/ml). The effect of apomorphine is antagonized by haloperidol. Probably, a dopamine system is involved in the neural control of the electric organ.