Investigations into the effects of concentration and duration of exposure to formalin and malachite green on the survival of the larvae and juveniles of the common carp Cyprinus carpio L. and the sharptooth catfish Clarias gariepinus (Burchell).

Prophylactic dip treatments using formalin and malachite green were applied to 4-day old larvae and 12- and 20-day old juveniles of the European common carp, Cyprinus carpio and the African sharptooth catfish, Clarias gariepinus. Treatments consisted of 100 mg/l malachite green for exposure periods of 10, 30 or 90 s and 200 mg/l formalin, administered for 30, 60 or 90 min. Larvae and juveniles of C.

Treatment of Cyprinus carpio L. and Clarias gariepinus (Burchell) embryos with formalin and malachite green: effect of concentration and length of treatment on their survival.

Malachite green and formalin were investigated as prophylactic dip treatments for developing embryos of Cyprinus carpio and Clarias gariepinus. Based on the findings, recommendations are made on the respective concentrations to be used and exposure periods to be followed for both formalin and malachite green for both fish species.

Some observations on the narcotizing ability of electric currents on the common carp Cyprinus carpio.

Some effects of alternating current electronarcosis and of rectified current electronarcosis on C. carpio were investigated. In all instances recovery from narcosis was accompanied by convulsive spasms.

The use of electronarcosis as anaesthetic in the cichlid, Oreochromis mossambicus (Peters). III. The effects of changing physical and electrical parameters on the narcotizing ability of half-wave rectified currents.

The narcotizing potential of various rectified current configurations on Oreochromis mossambicus was investigated. A 50 Hz, 200 Vp. half-wave rectified current, applied for 30 s, was found to be a suitable configuration for electronarcosis.

The use of electronarcosis as anaesthetic in the cichlid, Oreochromis mossambicus (Peters). II. The effects of changing physical and electrical parameters on the narcotizing ability of alternating current.

The effects of wave form, voltage, frequency and current as well as application time on the narcotizing ability of alternating current were investigated. A 60 Vrms, 50 Hz sine wave current applied for 30 s produced narcosis of sufficient duration to enable handling and blood sampling. A triangle wave form was inferior in narcotizing ability to both sine wave and square wave forms.