Effect of exposure to malachite green solution on common carp fry with Dactylogyrus vastator (monogenea) infection

In five experiments, common carp (Cyprinus carpio) fry with Dactylogyrus vastator (Monogenea) infection of different severity, as well as parasite-free fry, were placed into aquaria containing malachite green solution of 0.5-10 mg/l concentration. Most of the fish died within 6 hours. The correlation between the time of death and helminth infection was studied. The experiments demonstrated that in malachite green solution the carp with the heaviest helminth infection died first while the less severely infected specimens survived for the longest time.