How Did My Fish Get Ick?

Ick is one of the most common ailments affecting both freshwater and saltwater aquarium fish. Most fish keepers will have to cope with it at some point, and almost all fish are exposed to it in their lifetime, especially if they are kept at large retail chains. Ick is a parasite that causes small, white spots to appear on the fish's body, and it can seem to strike out of nowhere. Usually, though, there is a cause for the sudden appearance of ick in a tank.

  1. New Fish

    • The primary reason that otherwise healthy systems see an outbreak of ick is that new fish have recently been added to the aquarium---especially if those fish are added without a quarantine period. Sometimes new fish do not show outward signs of illness but still carry the parasite for ick. When they are transported into a new tank, they can either begin to develop the illness's characteristic white spots or pass the parasite on to the other fish in the tank without ever showing signs themselves.

    New Plants

    • The parasite that causes ick can survive off of a host for only about 48 hours. Unfortunately, many fish keepers do not quarantine new plants as they would fish, and if a plant specimen comes from an infected tank, there is a risk that the parasite may be introduced to your tank when you bring home live plants or decor. Always quarantine plant specimens in the same way as your fish to avoid this problem.

    Stress and Injury

    • Stress is also a frequent cause of ick in aquarium fish. Because it is possible for some fish to carry the parasites at low enough numbers to not display symptoms, ick may be present in the tank without your knowledge. Stress makes fish more susceptible to illness, and the fish's immune system may not fight the parasite as effectively as it would normally, allowing the illness to spread and break out in earnest. Injuries can also lead to ick outbreaks indirectly by way of the same process, and even minor wounds can allow further spread of the parasite if a fish rubs an injured body part against infected plants/decorations.

    Weakened Immunity

    • Fish that are already suffering from a weakened immune system because of poor breeding or genetic disorders may also be more likely to break out with ick. Because most fish are exposed to the parasite at some point, many fish develop a degree of tolerance for it. But fish that have immune deficiency problems lack this same ability to bounce back and may be overcome by repeated infections, which then spread to their tank mates.

    Water Quality

    • Water quality, important to the home aquarium in so many ways, can also play a vital role in the prevention (or spread) of ick. Infrequent water changes and poor water quality provide the perfect recipe for illness and disease. The parasite's numbers are allowed to grow unchecked when the water is not changed regularly, and the stress of an unhealthy environment can make the situation perfect for an outbreak. Maintaining good water quality with frequent small water changes is a step toward overall fish health and reduced illness.