THE NATURE OF DISEASE IN YOUR AQUARIUM: Disease organisms such as parasites, pathogens and bacteria are always present in your aquarium, however, under normal conditions they will not trouble your fish as your fish have an effective immune system just like humans. The best way to avoid disease is therefore to avoid the numerous causes of stress such as: a weakened immune system as a result of bad water quality (In over 80% of cases, bad water quality leads to a weakened immune system which sparks off disease). noise or vibration (for example a child banging on glass). new disease organisms introduced into the aquarium via new fish/plants. bad diet / not varied enough. Some fish may out compete others for food. overfeeding or wrong food type. 'unnatural' environment - allow hiding places for your fish. bullying from other - Keep fish that can live in a happy community. inadequate filtration / aeration. unsuitable water chemistry. overstocking. rushed water changes / water quality adjustments causing 'osmotic' shocks. Disease can essentially be prevented by: eliminating the causes of stress outlined above. maintaining healthy water and a 'clean' aquarium by following recommended maintenance. quarantine new fish. use a disease cure regularly as a preventative measure and always with new fish and plants. Determining Disease. Disease diagnosis is the first step toward successful and rapid disease cure. Most fish diseases are highly contagious and spread quickly in aquarium conditions so prompt diagnosis and treatment is advised. There are some 'early warning signals' which should be watched for as these can indicate the onset of a disease. Skin :- The skin is the first line of defence and as such it is often the first to show signs of attack from infection. Any changes in skin colour or appearance should be closely watched for. Fins :- Watch your fish's fins. Fins which are held close to the body signal an illness, particularly on live bearing fish. Swimming Behaviour :- Unusual or sluggish swimming behaviour can indicate the onset of a disease. Feeding:- If fish differ from their usual feeding pattern or stop eating altogether, then this could indicate the onset of a disease. Some diseases are very difficult to diagnose or can be diagnosed incorrectly. For example, Fungus may result from another problem such as Finrot. Therefore, it is important to treat the root of the problem (Finrot) as well as the resulting secondary infection (Fungus). But in most cases it is more effective to keep an eye out for a variety of symptoms which fish tend to exhibit when they are infected. These symptoms include: shaking of the head. lying near the water surface. shimmying (body rocking). cloudy eyes. slimy skin / red skin inflammations. skin patchiness / discolouration. bloody patches. open wounds / bleeding skin. rough scales / scale loss. mucus patches. breathing difficulty. rapid gill movement.