Diagnosis of Marine Aquarium Diseases

A definitive diagnosis is required before noninfectious diseases such as high nitrate, low dissolved oxygen, or poor nutrition can be accurately treated. It is not however always necessary to obtain a definitive diagnosis before an infectious disease can be properly treated.

The proper course of therapy can generally be selected from a tentative diagnoses based upon clinical signs and gross pathological changes. Ideally it is best to isolate the causative organism, do drug-sensitivity tests, and begin searching for clinical findings. This is not practical if you only have one sick fish.

It would be ludicrous to sacrifice the sick fish for a complete laboratory work up so you could know what it had and how it should have been treated before you killed it. If you are an importer and hundreds of fish developed acute clinical signs of disease then a definitive diagnosis would be necessary from a laboratory. It would also be important to do an antibacterial sensitivity test and try out the treatment on a few fishes prior to subjecting all of the fishes to your drug of choice. The average salt water hobbyist however will generally need to rely on the powers of observation and rational thinking to diagnose fish disease conditions.

Every marine hobbyist should have the capability to derive a tentative diagnosis from the clinical signs of disease in the living fish and from the gross pathological changes which occurred in the diseased fish. Remember it is not necessary to diagnose a condition any further than is required to institute proper therapy. If you diagnose the disease to a bacterial infection and treat it with the appropriate antibacterial agent, that is all that counts. It is really of only academic interest to know the specific bacteria that caused the infection.

Unlike human medicine where disease symptoms can be verbalized, veterinarians are forced to find out where lesions are without a conversation with the patient. In much the same way you will need to rely heavily on the powers of observation to determine which disease you are confronted with and how it occurred.

You will want to know the cause of the disease in order to select the proper course of therapy. The easiest way to establish the cause of disease is to observe the clinical signs and pathological changes. That is the order in which you will see them in your fish.