My Fish Is Ill - What Do I Do?
Fish can become ill for all sorts of reasons, but most often it is due to stress or incorrect water conditions. The basic two things to do when fish become ill is to identify the cause and select a suitable treatment.
Most health problems cannot be effectively treated until the cause has been eliminated. Check things like basic water conditions (ammonia, nitrite, nitrate levels), whether any other fish are affected, and if they are the same type or a variety of species. If only one fish is affected and there are no obvious signs of disease it may be a one-off.
Prevention is better than cure so making sure your aquarium provides the right environment is crucial - look at the fish types you have and ask whether there is enough room, the right kinds of hiding spots, the right substrate, and the right tankmates.
If there are obvious symptoms such as lumps, spots, cloudy patches or skin problems, try to get a good picture with a digital camera - you can then take this to your retailer and they may be able to identify the problem, along with any other information you can provide.
Reading through our Health and Diseases section should give you some idea of cause and remedies.