Common injuries for aquarium fish include nipped fins, missing scales, damaged eyes, abraded barbels and dislocated jaws. Physical damage appears suddenly, so should be easy to tell apart from developmental abnormalities caused by poor genes or diet.
There can be many causes of physical damage to your fish including fin-nipping and fighting
Small tears in the aquarium fish’s fins often reveal the presence of fin-nippers, pufferfish, tiger barbs and black widow tetras being amongst the most notorious.
In aquaria, the most common reasons for injuries in aquarium fish are handling, fighting, fin-nipping, unsuccessful predation, and various types of collisions and abrasions.