The pop eye fish disease, also referred to as exophthalmus, is a condition in which one or both eyes appear really huge and bulging. The bulging may grow to such an extent that the fish appears really hideous. Besides protruding in a grotesque manner by pooling of fluid in the eyes and the region surrounding it, it is quite harmful. Moreover, the eye lens appears cloudy white and if this condition aggravates, the appearance of a white ring is seen circling the eyes. Causes Pop eye disease in fish may be caused due to a combination of several problems or may be the symptom of an underlying bacterial infection. The fish can be infected by bacterial infections in various ways such as improper or rough handling, overcrowding, temperature fluctuations in the water, poor water quality, undernourishment due to poor diet, vitamin A deficiency, excess lighting, or even stress. The infection can also be spearheaded by previous diseases that had infected the fish and can also be caused by parasitic infestations or internal metabolic system disorders. Treatment Pop eye disease in Goldfish or cichlids is easy to identify, but quite difficult to treat. The simple reason why it is so difficult to treat is because the pop eye can be caused by various factors, and zeroing on the exact causative factor is not easy. However, what can be done is trying and looking for certain symptoms and carrying out the treatment as mentioned below. Case 1: If both the eyes of the fish are enlarged, then it's most likely that the causative factor is a bacterial infection. In this case, get the infected fish out of the tank and put it into a spare, clean tank treated with Maracyn or Maracyn II, which will act as the healing tank. This treatment will get rid of the infection from the fish. The same process is useful to treat injury caused to the eye due to scraping it on a rock or injuring it in a fish fight. Make sure that the healing tank is a bare-bottomed one with no decoration. Also maintain very little light penetration. Case 2: If the disease is not confined to just one fish, but is present in several fish at the same instant, then there is a probability that water quality is the problem. Water quality is often the cause for diseases to spread in fish. Thus, quickly resort to restoring the water quality in the tank. Start off by changing 30% water for the next 5 days or so and keep testing its conditions. Also check the ammonia and pH levels. On a general note, one should add one tablespoon of aquarium salt per 5 gallons of the water in the tank to assist the process of osmoregulation. Several antibiotics, injections, and other medications are available to treat this fish eye condition. The pop eye fish disease is mostly not a life-threatening one, although at times the bulging eyes of the fish do not completely heal and remain slightly larger than usual even after complete recovery. The best way to keep this disease, that attacks gold fish, cichlids, and all other fish in your aquarium, at bay, is by maintaining the fish tank regularly. Proper maintenance is the key to lowering the incidence rate of this disease. Poor water quality conditions will trigger all such diseases in your fish, which is why as a responsible pet owner, one is supposed to check for water quality and other parameters on a regular basis.