As with all aspects of medical analysis, a good history is critical in establishing a diagnosis. Specific questions are important to assess the environmental quality and may play an important role in treatment recommendations. First, a thorough description of animal housing should include the volume, design of the system, and source of water. The number and size of animals stocked, species (fish and non-fish), new additions, use of quarantine, decorations, plants, and previous medications are part of the case history and may also be relevant to assessment of environmental quality and system design. Owners can be asked to bring fish and water samples to the clinic, or the practitioner may wish to visit the site. Site visits allow the system to be more accurately evaluated and the behavior of fish to be readily observed. If a site visit is not possible, the owner can be asked to provide a video and/or photos of the system (including filtration) and the fish, both affected and unaffected. If fish are brought into the clinic for examination, a separate water sample should be provided in a plastic bag or clean, plastic water bottle. If the source water is from a municipal water supply, a second sample should be collected in a glass bottle for chlorine/chloramine testing. Water samples collected by the owner should be capped under the surface of the water without any gas bubbles visible. A minimum of 1 quart of tank water should be requested for regular analysis, and a second smaller sample (<100 mL) in a glass container for chlorine testing. If desired to use for recovery after anesthesia of the animal, a larger volume of tank water may be requested.