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How to Treat Sick Koi and Other Pond Fish

    Disclosure: We are not vets! The information below is based on our 35+ years of working with pond fish, as well as professional training from industry experts.

    Erratic movement, flashing or rubbing on rocks and surfaces throughout the pond

    • Possible Problem: Parasites
    • Treatments: Parasite & Ich Treatment, Praziquantel Treatment, Pond Salt, Probiotic Fish Food

    Large lumps or ‘warts’

    • Possible Problem: Benign Neurofibromas
    • Treatments: Rarely requires treatment; neurofibromas may fall off and regrow

    Growths that look like cotton balls

    • Possible Problem: Parasites
    • Treatments: Parasite & Ich Treatment, Praziquantel Treatment, Pond Salt, Probiotic Fish Food

    Open wounds or ulcers

    • Possible Problem: Bacterial Infection
    • Treatments: Ulcer & Bacterial Infection Treatment, Probiotic Fish Food

    Fins appear to be rotting away

    • Possible Problems: Fin Rot, Bacterial Infection
    • Treatments: Ulcer & Bacterial Infection Treatment, Probiotic Fish Food, Pond Salt

    Red streaks in fins

    • Possible Problems: Bacterial Infection, Parasites, Ammonia Poisoning
    • Treatments:  Parasite & Ich Treatment,  Praziquantel Treatment, Probiotic Fish Food, Water Change, Pond Salt, Pond Detoxifier

    Small, white spots that look like salt stuck to the fish

    • Possible Problems: Ich, Parasites
    • Treatments: Parasite & Ich Treatment, Pond Salt

    Gasping at the surface of the water

    • Possible Problem: Oxygen Depletion
    • Treatments:  Aerate the pond and agitate the pond surface, Reduce fish load

    Bulging eyes

    • Possible Problem: Bacterial Infection
    • Treatments: Ulcer & Bacterial Infection Treatment, Probiotic Fish Food

    Scales protruding from a swollen body (like a pine cone)

    • Possible Problems: Dropsy, Bacterial Infection
    • Treatments: Dropsy is difficult to treat; treat the pond as a preventative measure,  Ulcer & Bacterial Infection Treatment, Probiotic Fish Food

    Difficulty swimming underwater floating at the surface upright

    • Possible Problem: Swim Bladder Disease
    • Treatment: If fish are still feeding, feed with canned peas or Probiotic Fish Food

    Red or swollen gills

    • Possible Problem: Parasites
    • Treatments: Parasite & Ich Treatment, Praziquantel Treatment, Pond Salt, Probiotic Fish Food

    Learn more in our Ultimate Guide to Pond Fish Care.