Water quality can be easily improved by testing the water and performing a water change and tank cleaning. This stress, sickness or disease may have been caused by poor water quality, inappropriate living conditions (overpopulating an aquarium), or even the development of parasites in the tank. When they are aggressive, they are usually under stress, competing for food, or chasing down a mate.Īggressive goldfish are also often suffering from an illness or a disease that causes them stress. This may be one of those “self-explanatory” behaviors to many goldfish owners. When goldfish stay on the top of the water’s surface These options will help provide fresh oxygen filled water to the tank as well as remove any pollutants that may have built up to cause your fish to become ill and sit on the bottom of the tank. However, if your filtration system seems to be working just fine, then you may want to consider performing a 30% water change or cleaning the aquarium. If the filtration system does not maintain all three aspects of water filtration or, if the device is simply not working properly then, this issue will need to be corrected. The filtration system should have the proper mechanisms to maintain the chemical hazards in the tank water, the biological (algae) hazards, as well as the mechanical hazards (physical debris) that could be floating in the water. In this case, it usually means that your aquarium has not been cleaned recently, it has not undergone a water change, or the filtration system is not working properly. Goldfish that sit on the bottom of the tank is another behavior that may have an innocent explanation. When goldfish sit on the bottom of the tank Owners that do not address the underlying issue should expect to find their goldfish becoming severely ill and dying. If this seems to be the cause of the chasing behavior, then the fish will need to be separated, and the underlying cause (overcrowding, lack of food, etc.) will need to be addressed. However, bullying and fighting may occur if the fish are under stress (which is the second potential reason behind this behavior).įor example, if they are not being fed properly or are overcrowded then they may begin chasing and nipping at each other. Goldfish are typically very docile and are not likely to fight or bully other fish. This is not a sign of aggression, fighting or bullying. If this is indeed the cause for the chasing behavior, then you may not have anything to worry about. The first potential meaning behind this behavior is that the fish are courting each other or attempting to mate. When goldfish chase each other, it can be a sign of one of two things.

Small goldfish aquarium