Sunday, 1 August 2021

Mildew in fish

13 April 2021

Thrush, or saprolegniosis, is a disease affecting fish that is caused by fungus-like protists in the family saprolegniceae. Protists are found in every body of water, but they do not harm fish.

Mycosis in fish

Mycosis, which is a fungal disease, attacks fish that are weakened e.g. due to transport, as well as sick and mutilated ones, especially those that live in waters with low temperature. It is worth remembering that fish often get thrips after mating fights, during which their bodies are damaged. The source of infection are mycelium growing on various organic substances or dead animal organisms. Mycosis occurs when the eggs are dead or unfertilised. This is the case if the roe is silted up or cut off from the oxygen source. When the fungi develop on dead eggs they will attack the live ones as well. It is worth knowing that untreated water and a lot of decaying organic matter also contribute to the development of the disease on the eggs.

When the fungus attacks the fish's body, it can be seen in the form of thin, brown-white shreds. The fish are sluggish, inactive and rub against objects in the aquarium. Sometimes so called "fin sticking" takes place. When a bronchial infection occurs, the fish usually die as a result of suffocation. If the mycelium covers large parts of the fish's body, death can also occur.

thrush in fish

Mycosis in fish - treatment

How to fight thrush in fish? The key to success in this case is prevention. When fish are healthy, well fed and kept in good conditions, they will not become ill despite the presence of the mould fungus. Feces, food leftovers, dead fish or plant remains must be removed from the aquarium regularly to avoid the fungus invasion.

However, when the fungus has already infected the fish must be treated properly. It is worth placing the sick fish in a special treatment tank and gradually raising the temperature to 30 degrees Celsius. It is also worth to provide them with proper oxygenation and use therapeutic baths. There are also ready-made preparations available on the market, such as FMC, CMF or Mycoforte, which should be used according to the manufacturer's instructions. Water for therapeutic baths can also be prepared by oneself at home:

  • table salt - a solution of 20 mg per 1 liter of water is used in a bath lasting from 15 to 40 minutes.
  • copper sulphate - a solution of 1 g per 10 liters of water is used in a bath lasting from 10 to 30 minutes, such baths are used 2-3 times a week until the disappearance of the disease,
  • potassium permanganate - a solution of 1 g per 100 litres of water is used in a bath lasting from 30 to 90 minutes, such baths are used 2-3 times a week until the disappearance of the disease.

When the disease has affected valuable fish, the bath should be preceded by brushing the clusters of fungus with a solution of higher concentration. For this purpose you can use:

  • iodine - 1 ml per 10 ml of water,
  • potassium permanganate - 100 mg per 100 ml of water,
  • rivanol - 100 mg per 100 ml of water,
  • trypaflavin - 20 ml per 2 l of water.

Fish can be fed at this time.