Finding healthy fish starts with choosing a reputable store to do busines with. Some employees will get to know you and your tank, making it easier for them to help you with any problems you might encounter. The price of the fish is really much less important than things such as the quality of the fish, the knowledge of the staff and even how clean the store is. When choosing fish, look for danger signs of health problems. Cloudy eyes can indicate bacterial or oodinium infections.
Scales missing around the head or lateral line are often a disease symptom.
Extensive fin damage may be the result of fighting, whereas fins tha look cloudy can be the result of a bacterial infection. Any open sores on the body could indicate a bacterial or protozoan problem. White or black spots of any size are generally protozoan in nature. Thinness along the back or nape, not to mention belly, are signs of disease or malnutrition. A lack of interest in food, unusual shyness or other odd behavior are all possible signs of disease.