Parasitologic and histopathologic study of probiotic effect of Bacillus subtilis in experimental contamination with Ichthyophthirius multifilis parasite in goldfish

Ichthyophthirius multifiliis is one of the most important ectoparasites in ornamental fish causing economic losses. Although many different methods are being applied to reduce the prevalence of the disease but it is recommended to adopt preventive methods such as using immune stimulative materials like probiotics to support immune system of fish. This study was conducted to evaluate the effect of Bacillus subtilis probiotic on experimental infection of gold fish by Ichthyophthirius multifiliis. In order to do the research, 32 nearly same sized gold fish was used in two groups of 16 fish as the control and treatment groups and then the treatment group fishes was fed with Bacillus subtilis probiotic enriched pellets for eight weeks and after this time, the groups were experimentally infected with Ichthyophthirius multifiliis parasite and were tested for parasitological and histopathological purposes. Parasitological examinations revealed that the infection rate of the parasitic disease was significantly lower (P<0.05) in the treated group compared to the control group, in such a manner that the number of the parasites were 107 and 276 in the treatment and control groups, respectively. Histopathological examinations also showed that the fish in the control group had more lesions than the treated group (P<0.05).