Koi carps (Cyprinus carpio koi) are an ornamental fish variety frequently kept as pets in domestic ponds worldwide (Ott Knüsel et al., 2016). Fish diseases usually arise from a complex interaction of a variety of factors. The majority of problems affecting ornamental fish have multifactorial causes involving stress as a result of poor husbandry, poor water quality, overcrowding, and overfeeding. In a closed water system, such as a pond or aquarium, water quality analysis is an important procedure. The routine investigation should involve checking levels of ammonia, nitrite, nitrates, and pH; additional parameters such as hardness and dissolved oxygen may be required in some circumstances (Wildgoose, 2001). As an example of environmental causes of disease related to the pond, sunburn causes petechiation and patches of erythema on white and non-pigmented dorsal surfaces of exposed fish, and often occurs in shallow ponds where there is no shade and the water is exceptionally clear.