One of the biggest questions asked to the record breeder is "how do I determine the sex of my fish?" There are very few identifiers that are easy to identify in this process. Here we will discuss the methods used by some of the best breeders.
In juvenile fish, the determination of sex is almost impossible. This is only when they begin to mate as the opportunity presents itself to help in the determination of sex. Juvenile fish, both male and female, have a rounded dorsal fin, and this is only when they begin to mature that a difference can be detected. Since it is never wise to handle fish excessively, close observation is to help the breeder.
In Allnut Enterprises King's Discus Hatchery, for example, it is an easy process to determine who is who, as We have observed these fish for a while, and we can determine the sex couples That we possess. That would be true in any hatchery.
Some of the identifiers: The male will have thicker lips to help her fight to protect the female, and will be more aggressive. It is larger than the female, its forehead is thicker and we observed that if the disc is a little shy, the male will tend to remain between the female and the observer.
The dorsal fin of the male will be pointed, and the female's dorsal fin will be rounded.
The reproductive tube of the female, between the anus and the anal fin, is wider and rounder than the male, and will have a blunt tip. The male, in turn, has a smaller, sharper reproduction tube. It has been said that male discus fish will tend to have a less intense color and more pattern, while the female tends to be more colorful.
But with a lower model.
In an interesting article by Jeff Richard, [http://www.aquaworldnet.com/dbws/sexingdiscus.shtml] he discusses an article in the German Diskus Brief, a German publication, which reports a very successful way to determine the sex of one Disk using simple geometry. Jeff reports, and I quote: "Imagine a disc turned to your left … you look at it. Find the Dorsal (Top) and Anal (bottom) fins and look where the fins go down towards the Caudal) End … make sure you look at the fins after they have bent towards the tail. The dorsal and anal fins are almost (almost) converted straight after the fins are bent downward or upward … toward the caudal end An imaginary line along this straight section of the 2 fins towards the tail Which has just touched the Dorsals and Anal Fins past the Caudal Fin. These two imaginary lines must intersect behind the fish. The key to sexing fish is where the lines pass through. If they pass through the caudal fin, The fish is most likely a FEMALE. If they miss or just touch the caudal fin, it is very likely that it is a male. Thank you, Jeff!
Sexing Discus is difficult at best. The best way to do this is to raise a group of at least six to eight disks, and allow them to mate when ready. This is a nice sight to see this happen, and makes the hobby very useful.