What is it?
Velvet is quite common in aquarium fish, and affects all varieties. Its scientific name is Oodinium whilst other names include Rust, Gold Spot or Gold Rust. The parasite has a life cycle very similar to Ich, one of the most common parasites. It attaches to the fish, feeds, drops off then divides to form many more tiny parasites (up to 200!). These baby parasites then seek a new host and the cycle begins again.
Like most parasitic diseases, Velvet is generally only a problem with sick or stressed fish. It is opportunistic, as soon as a fishes immune system goes down slightly Velvet will attack. Common stresses include overcrowding, poor water quality, malnutrition, transportation or sudden temperature changes.
Goldfish are particular susceptible and unfortunately, the disease is very contagious and often fatal. However it is fairly easy to treat.
The fish will exhibit symptoms similar to ich. However the spots are much finer and appear gold or light brown. The spots resemble dust rather than salt (like ich). The spots are often concentrated around the gills.
Fish will also scratch against aquarium objects in an effort to remove the parasites. This can result in loss of scales and some skin damage. Some fish may over produce mucus as a barrier against the fish, so this is often a good sign when combined with other symptoms.
It may be hard to see the velvet, often the only sign is the damage done by the parasite. This damage may appear as dull or dark patches. Another way to see the velvet is to darken the room, and with a torch shine the fishes skin at an angle and look for the velvety appearance.
In more advanced stages the fish may become lethargic, have respiratory distress (breathing rapidly), lose its appetite and have clamped fins. When the fish is very ill it will look emaciated and will have lost weight.
Firstly, make sure the water is of a high quality, check pH and ammonia levels. Correct these and proceed with treatment.
Treatment is similar to Ich. General parasite treatments will work fine here. Copper based treatments, such as malachite green, work very well. These treatments may need to be repeated to ensure a full recovery. Remember to remove any activated carbon form your filter first, this takes medicine out of the water.
Salt added to the aquarium will make a great improvement. (0.6%) That's providing the fish can handle small amounts of salt.
Raising the water temperature slightly may also help, although that is not always possible.
See ich for information about the no-light approach, which has proved to work quite effectively. From the ich page ------ "Most commercial treatments will do the job, however these are often harsh and can damage the fish's protective slime layer. Often simply turning the aquarium light off for 7-14 days, and blocking most light out of the tank will do the trick. You can do this by taping paper to the sides of the aquarium, however lets some light in for the fish's benefit, and don't forget to regularly check the state of the fish. This process can damage the plants slightly, but not so much that they can't recover. The generally harsh chemicals from commercial treatments are worse for the plants in most cases killing them completely.
If the no-light approach does not work after about 2-3 weeks, the chemical approach can then be used. When using the chemicals, it is best to use them when the fish appears to have the least amount of spots on it, as this is the parasite's free swimming stage. The chemicals work best at this time, as they are not very effective in killing the parasite when it is attached to the fish. The chemicals may have to be used a number of times before the ich is completely gone. "------
Remember, water quality is always extremely important- so always check that first as it is often the cause of disease in aquarium fish. When treating sick fish, try to put the least amount of stress on them as possible, as stress will hinder the heeling process. Another thing is to remember is that generally, a healthy fish is a happy fish.
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