Support » Toolbox » Diagnose what’s wrong » Fungus and Bacteria

Our Diagnosis

It sounds like your fish has fungus & bacteria

How to be sure

Fungus and Bacteria infection can cause cotton wool like growths on the body, face or mouth. Your fish’s head or mouth regions may appear erroded and their fins could be tattered, frayed or blood streaked.

Step 1 – Treat your fish

Remember to remove the carbon from your filter prior to dosing.

Step 2 – Check your pond

  • When fish are sick, always test your pond water for excessive ammonia, nitrite, nitrate or pH imbalance.
  • Treat any unhealthy results to rebalance your water quality and give your fish the best chance of getting fighting fit again.
  • Check all your equipment is working properly – especially filters. Carry out any maintenance needed, or replace faulty or broken parts.


Blagdon fish medications can safely be used with Blagdon water and algae treatments.

If you want to re-dose, or change a fish medication, wait 7 days before beginning the new course.

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