White Spot in Freshwater


White spot (Ichthyophthirius multifiliis) is one of the most common parasites, most fish keepers have experienced this one first hand. It can affect all freshwater fish however scaleless fish like clown loach are more susceptible. It causes skin irritation and increased gill movement due to the parasite effecting oxygen uptake. As the name suggests an infected fish comes out in ‘White spots’ however white spot is not always correctly identified. These white spots are a little larger than a pin head. The parasite has stages both on and off a host fish but it’s only the free swimming stages which the parasite becomes susceptible to treatment. If left untreated mortality rate can hit 100%.


The parasite is not tolerant of temperatures above 32 degrees. To treat for white spot firstly increase the temperature to speed up the life cycle or directly kill (not possible in a pond). It is advisable to add an air pump to increase the oxygen as warmer water holds less oxygen. The parasites will all be at different stages so some will be affected by treatment and others won't therefore a course of treatment is required to kill the parasites when they become susceptible to the treatment. There are many treatments available under different names these are normally malachite and formalin based. Always check the water first before adding treatment as fish will never get better in poor quality water. 


  • Skin covered in tiny white spots.
  • Rapid gill movement.
  • Clamped fins.
  • Scratching and flicking on substrate and decoration.
  • Increased mucus production.
  • 'Hanging' in the water, moving little.

There are a number of treatments available either from your local aquatic shop or online. The below links are from Amazon UK and I have used these both of these myself so I know they work.

For the aquarium.....

 Or for the pond......


Please note if you buy from the Amazon links in this Blog article we gain a small commission for each purchase. This commission is used to keep our social media running, providing helpful, informative articles and content for our followers. Thank you for your support.