Freshwater Tropical Fish Diseases

Often an outbreak of disease happens when new fish are bought for the aquarium, and although the aquatic dealer is often blamed, it is not usually their fault, but because the new fish have become stressed from their change in environment and are therefore more prone to disease.

Except when starting up an initial aquarium, any further additions should be quarantined before being added in to the main aquarium.  Set up a small separate aquarium with a couple of rocks to give the fish a bit of security, and when any new fish are purchased keep them in this new tank for 2-3 weeks, and keep an eye on them for any symptoms.

Guidelines for Good Health

Don’t overcrowd the aquarium – this will get the fish stressed quickly

Don’t keep large fish with small ones, and provide hiding places

Don’t overfeed – this causes pollution

Don’t underfeed – a starving fish is less resistant to disease

Feed a varied diet – ensure the fish get all the nutrients they need

Avoid possible toxins from entering the aquarium – tobacco smoke, aerosols, paint fumes etc

Keep filters clean and make regular partial water changes

Avoid stressing the fish, don’t change the water conditions suddenly

Quarantine all new additions

Check new plants for snail eggs and other unwanted animals before putting in the aquarium

Remove any sick fish as soon as possible

Common Ailments

White Spot – this is the most common parasitic ailment and probably the easiest to diagnose.  The fish’s body is covered with tiny white spots, which extend to cover the fins.  The disease is of a cyclic nature, the parasite leaves the fish’s body to form cysts on the aquarium floor, these hatch, and then swim to find a new host.  This disease will affect the whole aquarium, so do not remove the affected fish, instead treat the whole aquarium with a treatment available from aquatic suppliers

Fungus – outbreaks of cotton-wool like tufts appear all over the fish’s body.  This only affects fish which are not in great condition, so there is no need to treat all the fish in the aquarium.  Remove the affected fish and give it a salt bath.

Mouth Fungus – this is caused by a slime bacterium and may not be cured by a salt bath as for fungus.  Get a recognised treatment from your aquatic supplier

‘Shimmying’ – the symptoms are aptly described, since the fish makes rapid undulating movements without any forward movement occurring.  The Black Molly is particularly susceptible to this, and the main cause seems to be a drop in water temperature, and the fish getting a chill.  Check the water heater and adjust if necessary.

‘Dropsy’ – occasionally a fish’s body becomes so bloated that the scales protrude, and this is caused by the body cavities filling with liquid.  It is difficult to cure, although some alleviation can be given by draining the liquid from the fish by means of a hypodermic syringe.  Dropsy is contagious, so remove the fish from the aquarium until it either recovers or dies.

‘Finrot’ – this is where either the tail or the fins degenerate, and this only occurs on fish of poor health.  Low temperatures, physical damage and unhygienic conditions all encourage the harmful bacteria.  Get the fish treated before it goes as far as the body, because once that happens it is not curable, and have a clean-up of the aquarium, maybe even doing a complete water change.

Gill Flukes – fish sometimes scratch themselves on rocks or plants, and accompany it with increased respiration and the gills gaping and inflamed.  Such fish are infected with parasites which burrow in to the skin or collect on the delicate gill membranes.  Treatment involves bathing the fish in a solution, available from your aquatic dealer.  The parasites cannot live without a fish host, so leave the aquarium uninhabited for a few days and they will all have gone.

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