External parasites
White spot: Ichthyophthirius multifiliis
Freshwater white spot, often called Ich, can spread rapidly. White dots are a clue, not a confirmed diagnosis.
What may be visible
Grain-like spots may appear on skin and fins, but gill infections can be less obvious. Irritation or breathing changes deserve attention even without visible dots.
Why one dose may fail
The parasite has stages on the fish and in the environment. Treatment timing needs to target susceptible stages and account for temperature. Obtain a confirmed diagnosis and follow the exact product and professional plan.
Do not guess from a photo
A mucus sample examined under a microscope can help distinguish Ich from lookalikes. Ask for prompt help; do not randomly heat the pond or stack medications.
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.