guides & articles

Related listings

Latest Postings

Subscribe to the hottest news, latest promotions & discounts from STClassifieds & our partners

I agree to abide by STClassifieds Terms and Conditions

Self-Improvement & Hobbies

Fungal infection

Will your fish get eaten up by a toadstool? Get your answers inside
CATS Recruit in The Straits Times - September 25, 2010
By: Wong Wei Chen
| More
Fungal infection

While relatively rare compared to bacterial and parasitic diseases, fungal infection is nonetheless a serious issue that needs to be addressed with promptness once fish get afflicted. If you’d like an appreciation of its urgency, just imagine a little toadstool sprouting up on the back of your fish, initially cute and tiny, but rapidly growing day and night, until one morning, you wake up to find that it has all but eaten up your pet fish.

Find that hard to swallow? Well, I can’t blame you, since I can’t imagine that too, and I don’t for a moment believe that toadstools actually grow on fish. But no harm having a little exaggeration to underscore the seriousness of the situation, right?

How it happens
Fungal spores are all around us. They are in the air, and they are in the water too. All fish tanks are therefore expected to contain a certain amount of spores.

When healthy, fish have a robust layer of mucus covering their bodies, which protects them from a variety of fungal infections. When stressed, sick or injured, the protective properties of this layer can be severely compromised, giving fungal spores in the aquarium an opportunity to latch onto the fish and proliferate.

Fungal infections, therefore, often come in the wake of injury that leads to torn skin, or bacterial and parasitic diseases that produce open wounds. Poor water conditions can also be instrumental in degrading the protection offered by the mucus layer.

Fungal infections first manifest themselves as grey or whitish threads or patches on the fish’s skin or fins. These become fluffy and appear like lumps of cotton wool when they propagate.

Fungal spores feed by secreting digestive enzymes onto the surrounding area. The enzymes break down tissues, enabling the fungi to absorb nutrients such as proteins and carbohydrates. In a manner of speaking, your fish is being eaten alive. (So my rather graphic illustration of a toadstool eating up fish wasn’t entirely off the mark!)

Common sense ought to tell you that fungal infections can be fatal if left untreated.

Fungal infections can be treated or controlled with the following kinds of medication:

Organic dyes
Organic dyes containing malachite green are often recommended for treatment. This type of medication is generally safe for most types of aquarium fish, but could be toxic to catfish, snails and other invertebrates.

Fungal infections are not contagious, so if you’re observant, chances are good that you’ll spot infections in one or a few fish early, and can therefore move them to a quarantine tank for follow-up. Treatment may take the form of a bath or direct application onto the affected areas, or a mixture of both.

Tea-tree oil
Tea-tree oil is sometimes preferred as a less toxic alternative to malachite green. It may, however, be inadequate in cases of severe infection, and is therefore best employed as a preventive measure before fish get sick. Consider this option when you see a distinct possibility of your fish getting physically injured due to fighting, fin nipping or rough handling.

While it could be effective at high dosages, the relatively low salinity-thresholds of many species of tropical fish dictate that salt be used sparingly. The effectiveness of this form of treatment is therefore limited. Even so, adding a small amount of salt to the water is helpful for keeping fungal infections at bay.

As proverbial wisdom tells us, prevention is better than cure. To circumvent infection, protecting your fish from injury is crucial. That means no rough handling, and populating your aquarium with a mix of species that can live together harmoniously.

Maintaining cleanliness is also an important consideration. Remove organic matter such as uneaten food, animal carcasses and dead plants promptly, and vacuum your substrate regularly to keep it clean. The cleaner your aquarium, the less problematic fungal infections are likely to be.


Can dogs and cats go vegetarian?