Protozoan Fish Diseases Australia

There are a number of protozoan diseases that can attack aquarium fish. To keep fish healthy it is important to provide a healthy environment. The water must be at the correct pH for the species, and a good filtration system is needed. To avoid possible contamination, it’s wise to quarantine new fish before adding them to your main tank or pond. Do not transfer their water with them. Always remove fish that look ill and don’t overstock the tank or over-feed the occupants.

The following gives an overview of some of the protozoan diseases which affect aquarium fish and suggested treatments. There are also specific Branded products you can buy from a pet store or aquarium to treat your fish.

1. White Spot Disease - Ichthyophthirius multifillis -pronounced ‘Ich’ or ‘Ick’. 

This is the commonest disease in home aquariums, in which the protozoa embeds itself into the gills or skin of the fish, resulting in fish irritation, hyperactivity and white nodules on the gills and skin. This disease can be fatal to fish.

Treatment involves removal of the infected fish for three days, and treatment of the water with quinine hydrochloride, quinine sulphate or malachite green, at 30mg per litre of water (although the latter tends to stain any plastic in the aquarium).

2. Infection from Trichodinia sp, parasite

These parasites attack the gills and cause breathing difficulty. Symptoms include scratching against objects, lethargy, and fish desperately coming to the surface to get oxygen. The fish body will also be darker than usual.

Treatment options:

• 30-minute, 1% salt baths for 2-3 days.
• 37%-40% Formulin: 250ppm for 60 minutes; 100ppm for 3 hours; 15-20ppm for longer term.
• Acriflavin: 50ppm bath for 2-4 days.
• Methylene blue: 100ppm bath for 2-4 days.

3. Infection from Ichthyobody sp or Costia sp

Symptoms include grey-white opaqueness of the skin, clamped fins, lethargy and rubbing of the skin.

Treatments:
Copper at 0.2mg per litre is the most effective, or salt bath at 3% solution. Raising the water temperature to 27-28°C for a few days may also be effective

4. Disease from Chilodonella sp Infection
This is considered to be the most deadly of the Protozoan parasites. It causes skin opaqueness, destruction of the gills, listlessness, clamping of fins and gasping for air at the surface.

Recommended treatments include Malachite green, Formulin, Potassium Permanganate and 3% salt baths.

5. Velvet or Coral Fish Disease -Dinoflagellates

Symptoms include a heavy yellow mucus secretion over the gills and skin, and fish flashing in the water.

Most effective treatment is believed to be copper at 0.2mg per litre, or alternatively Acriflavine at 1.0ml per litre.

6. Epistylis or Red Sore Disease -Hetropolaria sp

Fish with this condition display ulcers on the skin, spine and scales which result in a red-coloured lesion. This can be treated with 22g of salt to the litre for 30 minutes, or a continuous salt bath of 6g to the litre.