Sexing discus fish is not an easy task. There are a lot of different opinions online about sexing discus fish.
When discus fish are small under 4 inches in size their dorsal (back) fin are always rounded. Therefore it is impossible to tell if a young discus under 4 inches in size is male or female! If anyone that is selling discus claims to know male versus female and the fish is under 4 inches in size- they are probably lying to make a quick sale!
When a discus reaches 4 inches of size or larger the shape of the dorsal fin changes.
If dorsal fin is rounded on the corners = FEMALE
If dorsal fine is pointed on the corners – MALE
Also- a male discus is always larger than the female.
The shape of the dorsal fin is a good indicator of sex but not always 100% accurate.
Sexing discus correctly
The only true 100% accurate way to know determine sex of a discus fish is to actually witness them spawning.
The fish that lays eggs is obviously the female.
The male then swims over the eggs to fertilize them.
If you have a discus lay eggs but the eggs never hatch there is a good chance that you have 2 female discus.
At Discusguy.com we never guarantee the sex of a discus regardless of their size unless we actually witness them spawning.
Purchasing proven discus pairs
If you are looking to purchase a discus breeding pair be extremely careful and ask yourself and the sellers these questions:
1- If the pair is successfully spawning and producing fry why would they be selling them?
2- How old is the pair? The older the pair the less likely they will spawn.
3- How often to they spawn? If a pair spawns on a regular basis to produce fry to sell, the female may get burnt out and her health may be at risk. Reputable breeders make sure to give breeding pairs a break in between spawns in an effort not to jeopardize the health of the fish.
4- Where did the discus come from? Were they imported? Local breeder?
5- How many successful spawns have the pair had?
6- Why do they want to sell them in the first place?
7- Are they a PROVEN pair? If so, ask to see pictures of them spawning and pictures of the fry.
A less expensive alternative to getting a discus pair is to purchase 12 or more of the same discus strain/color when they are young. The odds of getting a breeding pair are usually pretty good. Many Discusguy.com customers have obtained breeding pairs in this manner.
I hope this information is helpful.
Feel free to contact me if you have any additional questions. I am always available to help.