Detailed Examination of Aquarium Fish Mortalities

Performing a necropsy on a recently deceased fish from an aquarium requires a persistent and inquisitive mind. For example let us assume that you just noticed your favorite clown fish go belly up and take its last gasp of air. Even though you are tired and had just settled back with your favorite music you jump up and remove your dead pet. Rather than grieve over the loss and flush it down the toilet you set forth on a detailed necropsy procedure. After placing the fish on a damp paper towel and grabbing your scissors tweezers and razor blade you're ready to begin a dissection.

But wait, take a close look at the external anatomy first. Is everything normal or are the fins frayed and one eye protruding? Say you only notice a one-sided pop eye. Are you going to quit there and jump to the conclusion that it died of tuberculosis and go back to your chair? Absolutely not. You are an inquisitive scientist and you are going to thoroughly check out every possibility within your capabilities.

What caused this eye to protrude? Was it from gas bubble disease? Although gas bubble disease occurs in marine fishes below hydroelectric dams its appearance would be extremely unlikely in a warm water marine aquarium. Perhaps an increase in intra-ocular pressure caused this eye to protrude? Some systemic bacterial pathogens can multiply and do damage within the eye itself. Others can multiply behind the eye and the subsequent inflammatory reaction can cause the eye to protrude. If a systemic bacterial infection caused this clinical manifestation of disease, pathological changes should be seen elsewhere; perhaps you overlooked the reddening and fraying of the fins. These signs indicate a loss of capillary and tissue integrity, which often occurs in a systemic bacterial disease.

Or perhaps this swollen eye has been caused by a buildup of body fluids, which often happens during kidney failure. If this is the case than other pathological signs of disease will likely be apparent such as a swollen abdomen. If you fail to notice these signs from the external examination you surely will pick it up on your internal examination. Your internal midline indecision would likely have brought forth a gush of free fluid from the abdomen. Your internal examination might reveal a swollen kidney and perhaps grossly visible lesions would be present. Then you can sit back and feel that you have made a proper diagnosis. Obviously kidney damage and undoubtedly add bacterial infection to the kidney would be a good tentative diagnosis. Now you have accomplished something.