There are different types of stress appears in the fishes due to several reason. In the aquarium it is necessity that the water must get maintain the pH level. Oxygenation in the aquarium is also important and the you must have to clean the nitrogen cycle. If you find any stress in the fish than you must have to check the water pH as well as oxygenation.
If your fish get the stress than another reason of stress is your fish get any infection or wound. There are different types of stress level in the fish to get the benefits.
Leavitt
