Can a Fish Be a Carrier of Ich?

Ich, or Ichthyophthirius multifiliis, infects tropical fish, goldfish and commercial fisheries. The protozoan spreads easily once it gets in an aquarium. Typically a new fish introduces ich, but infected aquarium water, plants, gravel and accessories could do it, too. Any time one fish in a tank is infected with ich, any of the fish sharing the tank can be infected, too.

  1. How Fish Carry Ich

    • To understand how fish carry ich, it's important to understand the life cycle of the ich protozoan. Juvenile parasites called tomites swim through aquarium water until they find a host fish. They attach themselves to scales or gills and burrow into the fish, where they feed on his bodily fluids, reproduce and form cysts. Those cysts create the classic white spots or patches for which the disease is named. When the cysts burst, the tomites escape into the aquarium water to find new hosts.

    Identifying Ich

    • Ich isn't hard to identify. Fish infected with ich have tiny white spots, like grains of salt, one one or both sides of the body or gills. The gills may appear slimy as the fish secrete mucus to soothe the infected spots. Because the protozoans tunnel into the fish's bodies to feed on blood and scale cells, they open wounds along the fish's bodies that are prone to infection. Fish rub their bodies against rocks, plants or accessories to scratch the ich spots, further damaging the skin. Infected fish have trouble swimming if fins on one side of the body are damaged.

    Treating Ich

    • Ich is easiest to treat during the tomite stage of the life cycle. When the tomites are swimming around in the aquarium water, they're unprotected and easier to kill. If they can't find a host during this stage, they die and can't reproduce. There are two methods of eradicating ich, raising the water temperature and using commercial preparations. To raise the water temperature, remove all of the fish to a separate aquarium. Raise the water temperature in the infected tank to 80 degrees F for 48 to 72 hours. Chemical preparations used to treat ich include copper sulfate, formalin and potassium permanganate. Follow the package directions carefully.

    Buying Healthy Fish

    • Since aquarium fish in the pet trade can carry ich, make efforts to buy only healthy, asymptotic fish. Purchase fish from reputable pet stores. Visit pet stores in person and examine all of the fish in the aquarium carefully before selecting your new pet. If one fish in the aquarium has ich, chances are that all of the fish are infected, and it's probably best not to purchase any fish from that particular tank. If you're not sure whether a new fish carries ich, keeping him isolated for 48 to 72 hours in a separate tank or aquarium to monitor his symptoms can keep him from transmitting the disease to healthy fish. If the telltale ich white spots don't appear after 72 hours, chances are good that the fish isn't a carrier.