Treating White Spot or Ich

You will notice the fish has a problem when little white specs become visible. They can appear anywhere on the body, fins or tail and look like a sprinkling of salt or sugar grains.

Understanding and treating White Spot (Ich) in aquarium fish

Often referred to as Ich or Ick, White spot disease is caused by the Ichyophirius parasite. Small numbers of parasites are naturally present in aquariums and are controlled by the fishes’ immune system. However, if your fish are weakened by stress (read more about fish stress here), the parasites take advantage. They increase in quantity until they reach dangerous numbers that can kill your fish.

The white spots on the fish are the mature stage of the parasites’ life cycle. The parasites create a home for themselves below the skin, so they’re protected as they feed.

White spots are typically 1mm in diameter, but if a fish is heavily infected these parasites cluster together giving the appearance of large white patches.

Understandably, white spot aggravates the fish, and they may scratch themselves on rocks or shimmy in the water to relieve their discomfort. Scratching can break the skin which may lead to secondary bacterial or fungal infections, so prompt treatment is essential.

After the parasites have stopped feeding from the fish, they break through the skin and drop to the bottom of the aquarium where they reproduce in a small cyst. When the cysts are ready, they burst open and release many new parasites into the water. The new parasites swim about until they find a fish to attach to and feed on, starting the cycle again. If they don’t find a host within a few days, they die. The ‘swimming’ stage of the lifecycle is important in the treatment of white spot as this is when they are vulnerable and medical treatments will affect them. 

It’s very important to understand the lifecycle of the parasites so you hit them with a treatment at the correct time (see diagram below).

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