Learn about the indications of fish fungal diseases and fish deaths
Saprolegnia. Usually secondary to other infections; it is not itself infectious.
CLUES: Cottonwool growth on any part of the fish. Low temperatures allow it to attack when the fish's immune system is at its least effective e.g. after spawning or after a long hard winter.
TREATMENT. Check water, particularly the Ph. Also check for physical damage.
Use a proprietary treatment or a Malachite Green bath - 2mg/l for 30 minutes. Some experts would recommend gently swabbing away as much of the fungus as possible with 10% solution of proprietary prepared iodine.
Branchyiomyces. This is a fungal disease that affects the gills of fish that stir up the bottom of the pool. It is not very common and has to have been introduced to the pool by new fish.
CLUES: New fish in the pool.
The behavioural symptoms are very similar to that of many other diseases i.e. lethargy, respiring heavily, not feeding, staying near the surface. The gills show cotton wool grows.
TREATMENT. Isolate and treat for fungus. It infects the whole system of the fish so quickly that it may be too late. So you may have to treat the whole pool.
Indications of bacteria
Aeromonas and Pseudomonas. These are external bacteria shown as ulcers, lesions or tear like damage on the body, fins and extremities of the fish. These bacteria are always present in the environment, but they are opportunistic in their invasion of the body of the fish. This opportunity arises from possible physical damage caused by bad handling, fighting or fin nibbling; stress caused by overcrowding and poor water quality are major factors in this.
Nitrites in the water can cause them to flick and rub themselves against solid objects. This may cause an injury that leaves them open to bacteria.
Also parasites like anchor worm, whitespot and fish louse can create a wound that can rapidly become infected by bacteria and develop into an ulcer.
If they are fancy goldfish, are they in too cold an environment?
Early behavioural symptoms - Lethargy, poor colour and emaciation.
Descriptive names of various types of bacterial infection are :-
Mouth fungus - reddened lips, loose white tissue around the mouth
Body deterioration/Body rot
Fin rot
Tail rot
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Cloudy eye
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Off white body film. Peeling.
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Buff spots like bread crumbs
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Red spots or red patches
Treatment
Treat the primary cause by improving water quality. This will help to reduce stress if the population of the pool is not too high. Dose with proprietary bactericide according to instructions.
Some bacteria can pass from fish to fish from infected nets so disinfect your nets in bactericide solution.
Isolate if the infection is bad.
Below 10C the immune system of most pond fish is not particularly effective. If however you wish to treat the fish effectively you must bring the diseased fish into a warmer environment but only very gradually. If you increase the water temperature too quickly then the bacteria with which the fish is affected with will take over before the immune system can get going. It is recommended that the temperature be increased by 1c a day until an ambience of between 18c and 20c is reached.
If ulcers or bacteria affect a large population of fish, after first attending to the quality of the water, a universal tonic of salt may be used at 0.5 oz. per gallon (3grms/ltr) of water. Unfortunately this will have detrimental effect on any aquatic plants. (See specific treatment for ulcers below.)
Vitamin C supplement with their food also helps.
Sudden death.
No real signs of the cause. This may be a caused by sudden changes in water temperature or the water quality producing stress that suppresses the immune system to the extent that the bacteria (Aeromonas and Pseudomonas) that normally populate the gills, skin and intestines of the fish get into the blood supply and poison it from Septicaemia. This can also result in Haemorrhagic Septicaemia or Ulcer disease.