Behaviour & health
Wounds, ulcers or red areas
Skin damage can progress. A photograph helps describe what you see but cannot establish the full cause.
Look without repeated handling
Record the location, size and appearance of the area and any change over time. Observe behaviour and breathing. Avoid repeatedly netting the fish solely to obtain better photographs.
Check the environment
Review water quality, sharp surfaces, recent transport or aggression. More than one factor can be involved, so improving a visible injury does not mean the underlying problem is solved.
Get qualified treatment advice
Contact an aquatic vet or experienced fish-health professional. Do not cut, cauterise or apply household antiseptics. Sedation and invasive care require appropriate expertise.
Prepare the details
Provide species, size, volume, complete test results, recent additions and every product already used. Tell the adviser if sturgeon or other sensitive species share the water.
Document without delaying care
If it can be done without extra handling, record the location and appearance of the wound and when it began. Include any previous treatment. Seek appropriate help rather than waiting for a larger collection of photographs.
Sources & further reading
Original WakeyKoi wording, informed by the references below. Linked clinical resources explain the evidence and their scope; they have not reviewed or endorsed this website.
Related guides
Educational guidance cannot diagnose an individual fish. Breathing distress, severe injury or unexplained losses need prompt professional assessment.