Ich Disease Treatment

Ich (Ichthyophthirius multifiliis) or white spot disease is one of the easier goldfish diseases to diagnose.

Ich disease, or as it is sometimes incorrectly called, Ick disease, is caused by a protozoan parasite.  The parasite penetrates the skin surface of the goldfish and feeds on its tissue and blood.

The irritation of the embedded parasite causes the epidermal (skin) cells to proliferate and form the characteristic small pinhead size white spots that form on the fins and body.  They are more easily seen on dark colored fish but are obvious when they start appearing on fins of lighter fish.

Ich is normally considered a tropical fish disease but is also found in the cooler water that goldfish inhabit.

Ich Disease Causes

An outbreak of the disease is frequently caused by a sudden drop in water temperature.

A more common cause is its introduction into the aquarium from a new arrival that hasn’t been quarantined.

Ich Life Cycle

Ich disease has four stages:

  • Free swimming stage, juvenile parasite looks for a host fish
  • Cyst stage (parasites embedded in the skin of the fish showing as a white spot)
  • Reproduction of the parasites by division within the cysts
  • The cysts break to liberate thousands of juvenile parasites into the water.

There is some debate when the division of the cyst occurs, after the adult parasite leaves the host fish, or while still embedded in the host. For treatment purposes it doesn't matter as the methodology is the same.

The speed of this cycle depends on water temperature.

If Ich disease is allowed to progress too far, the white spots will start to cover the head and gill surfaces causing breathing difficulties that eventually leads to death.

Treatment Options

The infected fish cannot be treated for Ich as the parasite is imbedded underneath the skin.  However, the parasite can be killed once the cyst breaks releasing the juveniles into the water.

The first step in treatment is to raise the water temperature gradually into the high 80s (30oC+) using an aquarium heater. This does two things:

  • The temperature is too hot for Ich juveniles to survive
  • It speeds up the parasite life cycle so it leaves the goldfish quickly. Prolonged infection weakens the fish.

There are several treatments that can be used.  The goldfish should already be in a mild salt bath:

  • Non-iodized salt.  The strength needed is very high, a pound per gallon.  The salt is not dissolved, but lies on the bottom of the aquarium.  Aeration can’t be used as it will cause the salt to mix in the water.  Weak fish won’t be able to take this amount of salt.  The objective is for the fish to swim above the salt concentrate, and the parasites fall to the bottom and into the salt where they are killed.   Use other methods if the fish is weak.
  • Quinine sulphate.  Dissolve ½ teaspoon per gallon.
  • Malachite green.  Most pet shops sell this chemical in convenient squeeze bottles for treating white spot.  Follow the instructions of the manufacturer.
  • Methylene blue.  Three drops of 5% Methylene blue in solution per gallon.

My preferred method of treatment is a combination of a mild salt bath with Methylene blue or malachite green added.

I gradually increase the salt content from two to 4 heaped teaspoons per gallon.  I then add the Methylene blue or malachite green.

When all cysts have disappeared after a few days, change 50% of the water without adding any chemicals.  Make sure the water temperatures are the same.

Turn off the aquarium heater and keep making daily water changes until all trace of the salt and chemical are gone.

As long as the fish is active and feeding well, it can be returned to its (sterilized) aquarium once the sickbay water temperature is down to normal.

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