Effects of Probiotic Treatment on Histopathology of Koi Carp (Cyprinus carpio) Infected by Myxobolus sp.

Koi fish (Cyprinus carpio) is one of the ornamental fish of a high economic value. However, raising koi can be troublesome due to poor water quality and high levels of stress that they are attacked easily by parasites. One of the parasites often attacking the gill of koi is Myxobolus sp. The presence of Myxobolus sp. can be observed through a histopathological observation of gill tissues. The purpose of this study was to determine the histological effect of probiotic administration to the damage on the gill tissue of Koi fish (Cyprinus carpio) infected with Myxobolus sp. The method used in this study was an explorative experimental method using factorial RAL. The observation of gill tissue was carried out on samples of koi fish consisting of two (2) control treatments, namely positive control (K+) and negative control (K-). Then, six (6) treatments, consisting of fish infected with Myxobolus and healthy fish, were done by applying a dose treatment of 1.1 ml/30 litters of water, 0.55 ml/30 litters of water, and 1.65 ml/30 litters of water. Treatments on control groups were carried out in a controlled tank by maintaining water quality parameters, which include temperature, pH, DO, and CO2. The level of gill tissue damage treated with probiotic formulations was determined by scoring analysis. The results of histopathological observations commonly showed tissue damage, namely damage to Edema, Hyperplasia, and Lamela Fusion. The treatment having the best influence according to the 5% BNT test was the PB treatment (infected fish with a dose of probiotic formulation of 0.55 ml/30l).