The majority of problems with pet fish are related to water quality. We highly recommend you have your water tested, and problems addressed before contacting the veterinarian. There are a number of resources online, including sources of water testing kits, and many pet stores that sell fish will test the water for you. Here is an excellent webinar on water quality from Dr. Jessie Sanders, a fish specialist in California.
If water quality is optimal, and problems persist, an appointment may be the next step.Fish should be transported in a large spill proof container, with additional secure containers of the fish tank water; this is in case the primary container spills, or we need additional water for testing and treatments.Common reasons for presenting to the veterinarian include external masses, parasites, buoyancy disorders, and trauma.