Koi & pond fish
Colour changes, new marks and missing scales
Not every change in colour is disease. The speed of change, skin texture and behaviour help decide what needs attention.
Take comparable photographs
Use similar light and angle, without repeated handling. Note whether a mark is flat pigment, raised tissue, a wound or missing scales.
Observe more than colour
New rough patches, excess mucus or a change in appetite deserve investigation. Ask a professional to assess lesions rather than treating all black or white marks alike.
Buying for the future
Young koi patterns can change as the fish develops. Choose a fish you like now, and ask about the individual listing rather than expecting a guaranteed adult pattern.
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.