The Weald Aquatics Blog - Bacterial Problems in Aquariums - another blog post from Weald Aquatics | Aquarium & Pond Fish Shop in Kent


Coolings Green & Pleasant
Main Road, Knockholt, Kent TN14 7LJ

01959 532 963

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and Public Holidays: 09:00 - 16:00
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Bacterial Problems in Aquariums

Blog post written by Gary | 09 March 2013 | Category: Aquarium maintenance

Bacteria can affect fish in a number of different ways in both external and internal infections. To minimise the risk of bacterial infections with existing fish, good water quality is essential. This can be achieved by regular water changes and keeping the gravel and filters clean.  Regular water changes will also help to keep algae problems to a minimum.

Internal bacteria can cause dropsy, where the fish develops a bloated appearance with scales sticking out from the fish; also fish can lose buoyancy and float upside down. Many unexplained deaths can also be due to internal bacterial problems.

With external bacterial infections, fin and tail rot and ulcers are the most common problems. The signs of fin and tail rot are ragged and split fins which, if not treated quickly, can erode both the fin and tail completely. Ulcers appear as open red sores on the body and again, if not treated quickly, can spread on the fish and to other fish in the aquarium.

External bacterial problems which are not so common are cloudy/pop eye and mouth fungus. A fish with the cloudy eye or pop eye will develop a whitish haze over the eye and/or the eye may protrude from the head.

Mouth fungus is not actually a fungal infection but caused by a common bacterium. The symptom of mouth fungus is usually white cottony tufts around the mouth, skin and fins of the fish.

There are many treatments available for bacterial infections. The two treatments we have found the most effective are the API Melafix and Pimafix for external bacterial problems, and Interpet No. 9 Anti Internal Bacteria for all internal bacteria infections.


A range of products are available for treating bacterial and fungal infections.
A range of products are available for treating bacterial and fungal infections.