Seasonal survey on bacterial, fungal and parasitic infections in rainbow trout culture farms of Qazvin province

A seasonal survey was undertaken on bacterial, fungal and parasitic infections in some rainbow trout culturing farms in Alamout region, Qazvin province during 2012-2013. Affected fish (totally 353 samples) showing clinical signs such as cotton wool, severe skin damage, flashing, eroded fins, exophthalmia, cataract and subcutaneous hemorrhage around mouth, fins, lens and muscles were samples three times a season. The phenotypic results showed that 69 samples were positive for Yersinia ruckeri and Lactococcus garviea the causes of yersiniosis and lactococcosis. Fifty six fish samples were also affected by fungal disease with cause of Mucor, Rhizopus, Saprolegnia and Fusarium. Also, a number of 62 fish samples were affected by at least one parasitic genus including Ichthyophthirius, Trichodina, Chilodonella, Gyrodactylus, Dactylogyrus and Ichthyobodo. Furthermore, the total abundance of the bacterial infections were 19-55%, with the most prevalent occurred for Yersinia ruckeri at the spring season (21.83%). Also the total abundance of parasitic infections was 17.56% with the most prevalent seen for Ichthyophthirius (11%) in summer time. The relative abundance of fungal infections was 15.86% with the most prevalent observed in case of Mucor (9.75%) in summer season.