Behaviour & health
Parasites, scrapes and diagnosis
Symptoms overlap. A diagnosis should guide treatment, rather than a shelf full of treatments guiding the diagnosis.
What a photo cannot tell you
Many parasites require examination and microscopy. Rubbing, lethargy or damaged fins can have other causes. A koi variety identifier does not diagnose infection.
Use the right help
A trained person can advise whether a scrape, gill assessment or other examination is appropriate. Handling and sampling incorrectly can injure the fish or produce an unhelpful result.
Before any treatment
Confirm accurate water volume, species, water chemistry, oxygen provision and previous treatments. Read restrictions and interactions for the exact product. Do not combine products because their names sound complementary.
Review the result
Follow the specialist’s monitoring and recheck plan. Keep a record of products, times and observations. Do not add new fish while an unresolved health problem is being investigated.
Ask for a named finding
When a sample is examined, ask which organism was found, where it was sampled and what follow-up is advised. Keep that finding with the treatment record rather than writing only that the fish had parasites.
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.