Upon suspecting trouble firstly check all the basic water parameters, if these are within the acceptable levels could it be that your last water change was completed with poor water? If you suspect this to be the case do another one and add some carbon to the filter, If this was the problem within twenty four hours you will see a return to the fishes former selves. Once the carbon has removed the pollutant throw it away. If a new fish has recently been added to the aquarium then it could of brought with it a parasite or two and passed it onto the existing stock. This is easy to identify as the fish will be breathing very heavily and flicking on the tanks decor as they try to rid themselves of it. Any proprietary anti parasite remedy from your local shop or from this site will solve the problem. Another fairly common problem, which is stress related and affects mainly small fish shortly after they have been purchased, is that they stop feeding and an internal parasite kills them over a period of time. In the initial stages of this illness the fish become nervous and darken, they pass their stomach lining, so their excrement appears transparent. If this happens in order to save the fish you must get it feeding again, try increasing the water temperature a couple of degrees to stimulate the metabolism. If this alone will not induce the fish to feed then treat the tank with an anti-internal parasite formula, such as the type manufactured by Interpet. Sadly if not recognised in the early stages this illness will be fatal. Tip top fish husbandry goes a very long way to preventing it so too does only buying the best fish you can afford.

Cloudy eyes are an indication of poor water conditions, a swollen eye is most probably a bacterial infection behind the eye. In either case establish good water conditions and treat any infection with a proprietary anti-bacterial product. Torn fins and general tardiness can be the result of transportation or a fight. In the case of breeding fish they become very worn out from the constant attention of their young. If you do not have a Ultra-violet steraliser fitted to keep the background levels of water born bacteria to a minimum then a coarse of a proprietary anti-bacterial solution will help.

The two ailments all Discus keepers fear but fortunately are far less relevant than most believe are commonly know as "hole in the head" and "Discus plague." Hole in the head was very much a problem in the sixties and early seventies and affects all Cichlids not only Discus. The fish darken, refuse food and a white cotton wool substance appears from small holes in the head area. Sadly by this stage it is too late and the fish die. In today's environment of better water conditions and controlled tank bred fish "hole in the head" is very rare indeed. "Discus plague" is again rare and as yet is little understood. The common denominator is that if it is going to happen it will strike when new seemingly healthy fish are added to an existing aquarium. The fish stop feeding, darken and look very ill, given time their own immune systems cope with it, but in the meantime loses may occur. Neither of these two ailments should deter a potential Discus keeper as I have said they are indeed rare, If you maintain tip- top conditions and purchase fish from established sources then the likelihood of ever encountering either of these two diseases is remote.

Article author Hans from Discusvis.nl