How to spot signs your fish is ill

Clamped fins: The fins instead of being splayed out (like a fan) will be closed up.


Heavy Breathing: You will see the fish move their mouth lots opening and closing and their gill plates moving in and out quickly.
The oscar in this pic is just being a grump, but you will see with a heavy breathing fish the mouth opening wide


Colour: The fish will not be as brightly coloured and look pale, or will show "stress" colouration ie, dark in general or dark lines.
Stressed fish new to the tank


Not eating: If a fish suddenly goes off its food it can be a sign that something is not right.

Position in the tank: Depending on the species of fish, some will rest on the bottom of the tank constantly, others will hang around near the surface or rest in plants for long periods of time.

Physical marks on the fish: Depending on the problem you may see spots (ick) wounds or leisons on the fish's body or fins.


The first thing to check is your water quality using a test kit. Test for ammonia, nitrates and nitrites, good water will show zero readings of all properties:



If you have ammonia, nitrites or nitrates showing, do an immediate water change and monitor the condition of the fish, if it improves the problem is down to the water, which most problems with fish are. Do not be inclined to think because just one fish is acting adnormally and the rest of the fish look fine that it is not down to the water. Some fish can tollerate traces of ammonia, nitrates or nitrites better than others.