Gas bubble disease was determined on rainbow trout (Oncorhynchus mykiss) ranged from fry to adult (250 g) in 12 fish farms in the Black Sea Region. We observed that the waters used in the fish farms. Generally, were obtained from a distant and high altitude location with closed pipe. And also, result of the study showed that the water in the pipe was not filling up the pipe and was observed the water was drained directly in the fish pond from the pipe. Dissolved oxygen, oxygen saturation and water temperature values were determined as 12.6-14.5 mg/L, 115.2-130.5% and 8.2-9.7ºC respectively in fry fish pond. These values in adult fish pond were 10.03-11.88, 116.9-139.1% and 20.3-20.9ºC respectively. To reduce to a value under 100% of the gas saturation in water were applied different precautions. As a result, the gas bubble problem was solved.