• Compare the size of your discus. Male discus tends to be bigger than the female.
• Take a good look at the dorsal and anal fins of your discus. If they are rounded then that’s a female and if pointed then it’s a male.
• Male discus forehead is little bigger & rounded that female.
• The colour and pattern of your discus, look at the colour and pattern of your discus fish, compare them to one another in the tank. Male discus fish tend to have less intense colour but have more pattern while the female tends to be more colourful but with lesser pattern.

Note: These are only guides and they are not always 100% correct as in some circumstances females having male characteristics and males have female ones.