Ick in Tropical Fish

When dealing with tropical fish illness and disease, it's always a good idea to have a good guidebook at your side. We recommend this book as a handy desktop reference.

One of the most common illnesses you will encounter with tropical fish, is “ick”, a disease caused by the parasite ichthyophthirius multifiliis. Translated, the term means “fish house with many children”, and for good reason.

The trophozoite, or parasite in its feeding stage of the life cycle, burrows under the mucous coating and first layer of the fish’s epidermis, irritating the skin so that a layer grows over top of it, and forms a bump. The parasite then feeds on red blood corpuscles as it grows, and when mature, it breaks free of the encapsulation. It then drifts to the bottom of the tank, or may fall onto plants or ornamental figures, where it goes on to form a cyst and reproduce asexually. By the time the pustule is ready to burst, there are hundreds of tomites, the free-swimming stage of the parasite, waiting to rush forth and find a new host.

What to Do About Ick

Because it is such a contagious condition, the threat multiplying rapidly as the parasite reproduces, it is advisable to treat the tank, even if you manage to catch the first fish in the stage where ick is just developing on its body. Remove that fish to a hospital tank, and then treat your entire aquarium against the chance of tomites already being loose in the water, or more cysts being present where you can’t see them.

Ick cannot be treated in the stage where it is under the skin. You can effectively treat either the cyst or tomite stage, with malachite green, aniline green or formalin. Raising the salinity of the water to its maximum tolerance by the present inhabitants also helps, as the ick parasite reacts poorly to the salt. Another tip, is to raise the tank temperature, as this will speed up the life cycle of the parasite, and it will enter the tomite stage more rapidly, where it can be effectively killed off.

While you are treating the tank with medications, be sure to remove and wash plants, ornaments, and your gravel. You may wish to remove all of these for the duration of treatment, to ensure there are no lingering cysts.

Under normal conditions of water at 68 degrees Fahrenheit, the parasite will live out its natural life cycle in about 55 hours. But due to its reproductive capacity, prompt treatment is an absolute must to stop the infestation.

How Does Your Tank Get Ick?

Ick can be brought into a tank by fish who have already contracted a parasite under its skin, or on plants from an infected tank. When purchasing from a pet store or fish dealer, be sure to inspect the other fish in the tank, as well as any ornamentation and the gravel. Look for fish with tiny lumps on their skin, particularly around the gills, or jelly-like cysts on the aquarium accessories and tank bottom.

Recommended! A-Z of Tropical Fish Diseases and Health Problems: The aim of this book is to help aquarists recognize signs of illness so they can identify and resolve problems. Divided into three sections, the first focuses on health and husbandry, describing the signs of a healthy fish, anatomy and general care; the second provides signs of diseases and health problems and is cross-referenced to section three, which covers the treatment of diseases and health problems. Illustrated throughout with top-quality color photos, the book is an invaluable reference for novice to experienced fishkeepers. Click here for your copy.

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