BETTA FISH CARING

Diseases that can affect Betta Fish

Oödinium pilularis (Velvet)

These notes are for educational purposes only. Attempts have been made to verify the accuracy of this document, but you should consult your normal qualified expert such as a Vet. If you decide to act on this information without consulting such an expert, you do so at your own volition as I cannot be held responsible for action you take. This said I have made it my business to check and re-check everything that has been inserted here.

Oödinium pilularis is also known as Rust, Gold Dust Disease and Velvet

In cultured fish this is one of the more common diseases. Capable of destroying the whole of a fish population before you even know it is happening or that you have a problem. This tiny parasite strikes both saltwater and freshwater fish equally without compunction.

Velvet in freshwater fish is caused by or Oödinium limneticum of Oödinium pilularis, whereas in saltwater or marine fish it is caused by Oödinium ocellatum. These three parasites are all very similar to Ich a very well known parasite. The parasite uses flagellum (a slender tapering narrow outgrowth of the cells of many micro-organisms, for example protozoa, that is by itself or in groups, a means of locomotion) to attach itself to the skin of the fish and then forms rod pseudopodia (a temporary cytoplasmic protrusion in amoeba and other protozoa used for locomotion and to take up food) with which it penetrates the gill filaments and skin.

The parasite is allowed to feed on the nutrients inside the fish by destroying the surrounding cells. When the parasite matures it divides itself into dozens of cells these cells drop off the host fish and spread themselves around the tank searching for new fish to act as their host and hence their food. If these new cells don’t find a host, they will die within a day. When they are on their host fish the parasite forms a white pustule (a small round raised area of inflamed skin filled with pus) not unlike that of the Ich, but much, much finer. They are not normally seen in time to treat the fish and sadly it is usual for the host fish to die. Unlike the Ich, which are not a common occurrence, these are very common and live in pet store tanks, laying dormant. They only become lethal if the fish become stressed, so it is imperative that the fish are kept in a stress less environment.

The symptoms to look out for are:

  • The fish trying to dislodge the parasite by scratching against hard objects

  • Loses appetite and becomes lethargic and sluggish

  • Loses weight

  • Rapid gill movement (this is an universal sign of illness)

  • The fish will be clamping their gills against the body

  • The skin takes on a yellowish/rusty colour (even though this is hard to detect, it is a tell-tale symptom. If you have a slight idea, try shining a torch beam on the skin in a dark room)

  • The skin will eventually start to peel away.

This parasite likes the following fish:

  • Goldfish

  • Zebrafish

  • Killfish

  • Danios

  • Anabantoids

Even so it still affects all other fish, from the fry stage to old age.

Oödinium is normally in its advanced stage by the time you have diagnosed the problem. This being so it is imperative that you start treatment as soon as you possibly can. Make sure the water temperature is around the 82 – 85 degree Fahrenheit mark as this speeds up the treatment. Keep the aquarium in dim light for several days as the parasite is very dependent on light. The fish will find it hard to breathe, so add a quarter of a spoonful of AQUARIUM SALT (not table salt) each time you change the water.

For ten days, treat with copper sulphate. You can also use Quinacrine hydrochloride (follow instructions in package) and Atabrine. You are trying to kill the parasites that haven’t yet found a host. During the course of treatment discontinue filtration as carbon filters take all the medications out of the water, destroying your good work.

 

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