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White Spots

Question: My Fish are covered in little White spots

Answer: Good News and Bad News. The bad news is you have White Spot, Ick for short. The good news is, it's treatable if caught early.

The disease is caused by a protozoa, a small parasite, Ichthyophthirius multifiliis, and is highly contagious. These parasites borrow into the fish's skin where they spend part of their life cycle feeding on the body tissue. They seal themselves in by secreting a small white cyst which is the characteristic white spots we see on the surface. When adult, they emerge from these cysts and drop to the floor of the aquarium, where they multiply inside a protective capsule. Some time later, the capsule bursts, releasing hundreds of free-swimming infectious parasites which attach themselves to new fish hosts.

White spot is very much an opportunist, (a bit like the common cold), always around and just waiting for a chance to get going. Outbreaks of white spot often occur after fish have been been stressed by traveling or cooler than normal temperatures, but the most common cause by far, is poor water quality. For this reason it occurs most frequently in newer aquariums were the fish keeper may be inexperienced, both in maintaining the filter system, and in spotting the symptoms early enough to seek effective treatment.

Some fish are more susceptible than others. Clown loaches are particularly prone to white spot, but there are very few species which won't be affected once an outbreak gets going. Prompt treatment is essential, and there are several effective treatments available.

The parasite is only vulnerable during it's free swiming stage, whilst inside the fish or when multiplying it is totally protected by the white cyst or its protective capsule. To be fully effective any treatment must be active for at least the full life cycle of the parasite, typically 5 days. Raising the temperature slightly to 27°C - 30°C reduces the time taken for the parasite to complete it's life cycle and can aid treatment. It is necessary to treat the whole aquarium, removing an infected individual to a quarantine tank will not stop the outbreak.

Maroon Clownfish in an Anemone