Affected fish usually show respiratory distress. There is prominent gill necrosis caused by thrombosis of blood vessels in the gills. The disease occurs most commonly in ponds with abundant organic matter, and high ammonia levels. Another chemical is the herbicide Diquat. Several chemicals have been used to treat BGD in hatchery salmonids.
Caution is necessary because the margin of safety is narrow, particularly in soft water.
Another chemical is the herbicide Diquat. None of these chemicals are approved by the U. S . Food and Drug Administration for disease control in food fishes. In hatchery tests conducted by the National Fish Health Research Laboratory, one treatment effectively controlled BGD when it was given early in an outbreak. However, two or more treatments are required for advanced outbreaks.