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Saltwater Fish Disease

By: Jennie Kermode - Updated: 10 Feb 2013 | comments

Every aquarist fears disease but treating outbreaks in your marine aquarium can be all the more difficult. How can you spot developing illness and what are the best ways to treat it without damaging your marine ecosystem?

Tropical marine fish are often particularly vulnerable to disease because of stress caused by being transported over long distances, especially if they have been taken from the ocean. Adjusting to aquarium life can also prove difficult and the stress involved can lower the immune system. Always ask your fish shop to order captive bred fish for you and you can avoid this problem. Avoiding wild-caught fish also means that you avoid the risk of introducing disease organisms from the ocean into your aquarium.

As with all fish diseases, the best option is not treatment but prevention. Maintaining stable water parameters well suited to the needs of your fish, using good filtration and selecting fish that get along well will vastly reduce the risk of disease outbreaks. Provide a suitable habitat, avoid overcrowding and supply suitable, nutritious food, and your fish should enjoy good health most of the time.

Detecting Disease

Despite all your precautions, it is inevitable that things will sometimes go wrong. When they do, the sooner you can treat your fish, the better their chances of survival will be. As always, good aquarium management requires paying attention. Look out for fish whose colours have faded, who are breathing more slowly or more rapidly than usual, who are behaving listlessly or who are suddenly being bullied by other fish. Odd swimming motions, scratching and folded-down fins can also be signs of trouble. If you notice symptoms like these, consider isolating the affected fish as you try to work out exactly what is wrong.When treating disease with medication, it is always best to do so in an isolation tank. This is especially important with marine fish as many marine organisms can be poisoned by copper-based medicines and other useful treatments.

Common Saltwater Fish Diseases

Saltwater Ich -Fish affected by this parasite will twitch and try to scratch it off their skins, hyperventilating and often darting about. They will gradually become covered by tiny white spots. UV or ozone sterilisation units can kill the parasite during its free-swimming stage. Copper-based treatments and malachite green can help, as can raising the water temperature.

Flukes - Affecting the respiratory or digestive system, these parasites rarely become problems unless general aquarium conditions are poor. They cause hyperventilation, loss of appetite, listlessness and dark patches under the skin. A freshwater dip can often get rid of them; otherwise, try formaldehyde or potassium permanganate.

Clownfish Disease -A big risk for clownfish, this can also affect other species. Symptoms are increased mucus production around the gills, ragged skin and loss of control of buoyancy. The most effective treatment is a formaldehyde bath, though copper solutions and malachite green can also help.

Lateral Line Disease -This illness is characterised by the development of open wounds around the eyes and along the lateral line, and its cause is unknown, though improving water conditions often makes it go away. Use an antibiotic to prevent secondary infections and try providing affected fish with extra vitamins and iodine.

Uronema Marinum -The presence of this parasite is first indicated by scratching and scraping. The skin of affected fish will fade, develop pale patches, and begin to peel. The eyes will become cloudy and the disease must be treated quickly to prevent blindness. Formalin dips are usually the most effective treatment.

Many of the medicines used to treat saltwater fish diseases are highly toxic. Overexposure can harm your fish, so you should always be very careful about getting the dose right. Most commercial preparations come with guides to make this easier. If you are uncertain about using such treatments or are unsuccessful in treating disease outbreaks, contact your local vet. Many vets are willing to treat fish or can refer you to specialists who will. Vets also have access to antibiotics which you may not be able to buy over the counter.

Although disease is something which happens in almost every aquarium sooner or later, it doesn't have to be a disaster. Good aquarium management and prompt treatment when problems arise will give your fish a good chance of living long, healthy lives.