White spot disease, also known as Ichthyophthirius multifiliis, or Ich, is a very common parasitic disease which affects fish and is highly persistent! Once these parasites are detected inside an aquarium, the disease is particularly difficult to stub out due to remarkably fast reproduction rates. In this blog we will talk you through some valuable treatments that can be used to overcome white spot in fish, as well as some common causes that are worth knowing about.


White spot is caused in aquarium fish when a protozoan attaches itself to their body, fins and gills. The contagious disease shows itself as tiny white spots on the fish’s body. These parasites appear like small grains of salt or sugar and can cause damage to a fish’s breathing ability as well as mobility problems. The parasites the cause white spot affect fish in two stages. The first “free” phase is where the parasites will rapidly reproduce. The second stage is where the parasites will feed off the tissues of the infected fish. During this infecting stage, the parasite will pass through any part of the skin by invading the area. Worst of all, once the parasite has finished feeding and infecting, it will release itself from the surface of the skin, gills and fins of the fish and drop to the bottom of the tank where it will then multiply, producing up to 2000 new parasites. It is therefore easy to appreciate just how fast growing the condition can be amongst a community of once healthy fish.


If an untreated white spot tank is left, a 100% mortality rate of aquarium fish can be expected. Fish that have become infected with white spot will show signs within the early stage of the illness such as disordered swimming and fins folded against the body. When the fish start showing signs of scratching themselves up against stones, it indicates that the parasites have crossed the protective mucus membrane of the skin and are now in the second stage of infection. Other signs include the recognized white spots which start off as a pin head size on the fins. They can be detected under direct light and continue to cover the surface area of the body where the fish may even be spotted swimming to the surface of the water more frequently, indicating that the parasites are affecting the gills and causing breathing difficulties. The parasites will eventually affect the eye muscles and peri-orbital tissues causing the eyeball to swell out.


So let’s explain a little about what causes white spot, along with some preventative measures before we go on to talk about the treatment for the condition:


It may be worth knowing that White spot can be triggered by stress caused by unusual changes to environmental conditions. Temperature conditions are particularly significant if say for example, cooler water is added to an already established water tank temperature. It is also worth understanding that parasites can be introduced into an aquarium if products are not fully cleaned once purchased from a supplier. The same goes for aquatic plants. Thirdly, introducing fish who are carrying the parasite can prove detrimental to the health of your existing fish. Fish sourced from a poorly maintained tank can soon infect a new, clean one. In order to look at ways to prevent white spot from ever occurring inside your aquarium, we need to consider reducing the risk of the above causes occurring. As temperatures can affect the environment of your aquarium, it would be a reasonable caution to maintain optimum levels of PH and temperature within your tank. Replacing old water with high quality water that has the same temperature as the community within the tank, is a sensible preventative measure for avoiding white spot. As white spot can be introduced from ornaments, decorative products, fish and plants that have come from infected environments, ensure that your fish and plants are sourced from healthy aquariums prior to releasing them into your tank. It is also worth considering observing a quarantine period of at least two weeks prior to introducing new fish into your tank, regardless of where these are sourced from to check for signs of any fish displaying signs of poor health. Boiling/sterilizing ornaments and decorative products will also help to reduce the risk of infecting your already-established tank. Finally, ensure that new plants are cleaned with a strong disinfectant before introducing them to your aquarium.  Caution, never boil aquarium rocks though as trapped air pockets can force the rocks to explode!


Now we will give you some guidance on how best to treat the effects of White spot in your aquatic fish:


You may be surprised to learn that it is possible to combat parasites of white spot by accelerating their biological cycle, decreasing the window of exposure opportunity, and ensuring that the medicines used are as effective as possible. By increasing tropical water temperatures to 30 degrees Celsius (and cold water temperatures to 22 degrees Celsius), white spot can be slowed down in its very early stages. In terms of targeting white spot with medication to ensure it is truly eradicated – this can only be done at a key stage in the parasite’s life cycle. Treatment such as anti-parasitic medications like Interpet's Number 6 Anti White Spot 100ml and King British WS3 will only be effective during the first free phase where the parasite is rapidly reproducing. Once the white spot parasites have entered their second stage and broken through the surface skin of the fish, treatment will unfortunately not work. When using anti-parasitic medications, they should be of the antibiotic type specifically for anaerobes so as not to affect any denitrifying bacteria found in the tank water.


Whilst medication is the most effective treatment type for tackling white spot, the preventative measures provided within this blog should serve as clear and useful guidelines to use in order to ensure that the conditions for white spot are non -existent to start with, allowing you to spend more time observing and enjoying your aquarium than anticipating the arrival of unwanted diseases!