How To Select a Discus?

Because Discus cost a bit more than the average freshwater fish, Discus hobbyist have developed several key factors to use in order to find the best of the best. Some of the following points I learned the hard way, most though have been taught to me from experienced hobbyist.

• Discus should be round shaped not wedge shaped. Either bad genetics or stunted growth is to blame for odd shaped Discus. Poor diet also contributes to this.
• Discus stomachs should not look like they are pinched. This could mean the Discus is not eating or is sick.
• Discus stomachs should not look bloated. This could mean that the Discus has a digestive blockage or worm infestation.
• Discus eyes should be smaller in proportion to their body. When the eyes are large for the body size of the Discus it means its growth was stunted by bad nutrition. There is no cure for this, no matter how much you feed it.
• Discus eyes should be clear not cloudy or dark. Cloudy eyes can be a sign of poor health or stress.
• Discus fins should be spread out and erect, not clamped down. Fins that are clamped down can be a sign of a stressed and sick Discus.
• Discus body color should be vibrant and bright not dark or black. Dark or black Discus that are not carrying fry are either stressed or sick.
• Discus should approach the glass of the tank when a hand is placed near the tank (not tapping). Approaching the tank glass is a sign of a happy Discus with a good appetite.
• Discus fins should be intact, not torn. Torn fins can be a sign of nipping or poor health.
• Discus should not have white or long stringy waste. This can mean internal parasites

Source: Discus Guide