Common Fish Diseases and How to Deal With Them

Fish ailments can range from their equivalent of a common cold to some debilitating infection that is beyond treatment. Diseases fall into two groups, those that have early external visible symptoms and those that don’t. The problem with the latter type is that by the time the fish’s behavior or eventual general appearance tells you something is wrong, it’s usually too late to effect a cure.

A similar disease to White Spot is Velvet. Caused by the parasite Oodinium (now Piscinoodinium) pillularis, the symptomatic spots on the fish’s body are far smaller, giving the impression of being ‘dusty’. Again the fish’s attempts to alleviate the disease are scratching, increased breathing and maybe some rusty patches of color appearing.

Treatment is to use a salt bath in a darkened tank (the parasitic spores often photosynthesize) coupled with a few degrees rise in temperature, if the fish can tolerate it. Trypaflavine is another alternative remedy, again with an increase in temperature. Amyloodinium ocellatum is responsible for Marine Velvet. Treatments include copper and freshwater dips.

Gill and skin flukes
These, literally, irritating ailments are caused by two separate, yet remarkably similar-sounding worm parasites – Dactylogyrus and Gyrodactylus. These creatures are armed with hooks by which they attach themselves to their unfortunate hosts which are soon debilitated by their blood-sucking attentions. Listlessness, loss of energy, faded color and difficulties in breathing are all symptomatic of an attack by these parasites.

Initial treatment in the hospital tank should involve a 25 per cent water change before moving on to recognized remedies such as formalin and organophophorus-based treatments, both of which should be handled with care.

Fin Rot
Not so much a disease as rather a secondary illness. Where a fin becomes split, it provides an excellent location for disease to invade. It is usually in poorly-maintained aquariums where water conditions are well below what is recommended and the tank’s overall hygiene has been neglected that such secondary diseases flourish. Transferring the fish to better surroundings usually affects a cure.

Caused by the fungal mould Saprolegnia, Fungus is again a secondary invader after the fish has been attacked by a parasite, has an open wound and is being kept in less than perfect water conditions. The disease looks like tufts of greyish cotton wool attending the affected area. Salt baths are beneficial as are proprietary treatments allied to improved aquarium hygiene.

Mouth Fungus
Although apparently sharing similar visible description to Fungus, this particular ailment is not caused by the same fungal mould but by a bacterium Flavobacterium columnare (formerly Flexibacter columnaris). Enouraged by poor aquarium conditions, the disease should respond to treatment with antibacterial remedies.

Neon Tetra Disease
Named after the Neon Tetra in which it was first found, it is caused by Pleistophora hyphessobryconis. Symptoms are fading of color on the fish together with subsequent wastage of muscles and loss of swimming ability with death being the inevitable outcome. All affected fish should be removed and destroyed as there is no reliable remedy.

This debilitating disease is not a pretty sight. The scales stand out almost at right angles from the body which has become distended through the build up of fluid internally. Gouramies seem particularly prone but there is no consensus as to the actual cause or whether it is as contagious as some believe. Affected fish should be removed for risk that other fish may eat their dead bodies and so contract the disease. Possible effective treatments include anti-internal bacterial remedies. Experimental drawing off of the bodily fluid with a syringe is not to be recommended.

Unfortunately, this disease is as distressing as its name implies with tiny holes appearing on the head and along the lateral line (where it is called Lateral Line Erosion). Certain Cichlids, such as Discus and Uaru, seem prone to this as are many marine fish. The cause is a parasite, Hexamita, but there are many opinions as to what triggers an attack from blaming poor conditions, stress and even carbon in filter. Remedies containing Metronidazole are said to be effective.

Sometimes you see a fish, especially Mollies, standing on the spot and gently swaying from side to side. According to some, this is not a disease, or anything affecting their balance, but merely their reaction to cool temperatures as raising the water temperature usually makes them stop doing it. Other sources feel that this may be the onset of symptoms caused by a massive invasion of many pathogens and bacteria, requiring at least a salt bath and perhaps the use of a proprietary remedy.

Swimming Disorder
Where a fish cannot maintain a definite position in the water, for instance, bobbing up or down, or tumbling head over heels when swimming then this is due to a malfunction with the swim-bladder. It is not an uncommon ailment in Fancy Goldfish, where the internal organs have been forced into restricted space due to the desire for a certain body shape on the part of the fish breeder.

Sometimes other internal disorders such as indigestion, can have a knock-on effect on the swim-bladder. Here, the remedy is to feed a wide and varied diet (including live foods) and to add a light laxative, such as Epsom Salts, to the food to clear any digestive tract congestion.

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