FIN ROT

 Of all the bacterial diseases that affect ornamental fish, fin rot is one of the most common. Part of this reason is that it is reasonably easy to identify, and partly it is because the bacteria that cause it are widespread in the aquatic environment.

  CAUSE

  Fin rot is a symptom caused by the presence of a number of different bacteria species, most commonly those of the Flavobacterium genus. In particular, Flavobacterium columnare has been identified from many cases of fin rot. Fin rot typically occurs when the temperature of the water rises above 15°C, and is more potent in tropical aquariums.

EFFECT

 The bacteria that cause fin rot typically infect the tail, rotting away the membranes between each ray. In severe cases, the infection may erode most of the tail and then progress onto the body of the fish. Fin rot is often associated with other symptoms of bacterial infection, including mouth rot and gill disease.

SYMPTOMS

 The first signs of fin rot usually involve a reddening of the fin and the appearance of a faint white line around it’s outer edge. This is followed by the progressive deterioration of the fin, giving it a ragged appearance. The bacteria that cause fin rot may also infect the gills, hindering the uptake of oxygen and forcing the fish to hang near the surface of the water. In addition, they can also cause mouth rot, causing the mouth to redden and erode. The site of any infection may appear to have a cotton-wool like growth around it, which should not be confused with fungus.

SOURCES OF INFECTION

 The bacteria responsible for causing the majority of fin rot cases are caused by “opportunistic” species. These are bacteria that are naturally present in the environment all of the time, and which will only cause infections under certain conditions. Outbreaks typically occur in poorly maintained tanks and ponds or when fish are damaged or stressed.
Excessive levels of organic matter provide an ideal environment for the bacteria to multiply, and poor water quality stresses fish, lowering their resistance to infection. Physical damage can also provide an entry point for the bacteria, particularly if the immune system is compromised due to stress.

PREVENTING INFECTION

 Given that fin rot can principally be thought of as an environmental disease, the key to preventing infection lies in properly managing your pond or aquarium. In order to avoid fin rot or to aid in it’s treatment, take note of the following:
1. Make sure water quality is good by providing the correct filtration and aeration for your pond or aquarium, and by avoiding overcrowding or overfeeding. Ideally, use TetraTest kits to check ammonia, nitrite, pH and nitrate on a regular basis.
2. Keep sediment levels low by routinely checking and, if necessary, removing organic matter from the gravel / pond floor. This will keep bacterial numbers in check and help to maintain water quality.
3. Regularly observe your fish for physical damage and treat any wounds by adding a general remedy to the water, e.g. TetraMedica General Tonic or TetraPond WaterSafe. Try to determine how the fish are being wounded and then remove the cause.
4. Don’t be tempted to turn pond filters off over the winter, or if you have to, make sure they are turned back on before the start of spring. This is a common reason for spring pond problems, which are commonly caused by opportunistic bacteria.  

TREATMENT

 In most cases, fin rot can be successfully treated with TetraPond MediFin or TetraMedica General Tonic. It is, however, important to treat at the earliest signs of infection to give your fish the best chance of recovery. In addition, as well as adding a remedy it is important to determine the cause of the problem and rectify it. Failure to redress any environmental problems will almost certainly lead to a recurrence of the disease.
In ponds, coldwater aquariums and tropical aquariums that contain species that are not salt-sensitive, adding a 3g per litre (0.5oz per gallon) dose of salt to the water can aid recovery. Always use salt purchased from your Tetra Club retailer, as this will not contain any harmful additives. Salt helps the fish to maintain it’s internal salt balance, conserving energy and reducing stress, and may hinder the proliferation of certain species of bacteria.
 

In properly maintained tanks, fin rot and many other bacterial problems are easy to avoid. Where outbreaks do occur, effective treatment is easy to administer, provided the problem is caught early on.  

 

 

The white outline and eroded fin edge indicate the presence of fin rot