Male Female Angelfish
In some cases it can be difficult to tell until you actually see the female laying eggs.
Male female angelfish. An enlarged bump on the head is also a sign of a male angelfish. Some of the traits you can look for to potentially identify a male can be. Male angelfish generally have a larger more circular body than the female.
A large bump on the forehead. Male vs female angelfish females have a swollen body during egg production but not the males unless they are overfed. Breeding habits of angelfish include cleaning a surface to lay the eggs on.
Crown shape is straight or slightly curved in females but it is highly curved in males. Male breeding tube is thinner and pointy much like a pencil tip. The most pronounced difference between the male and female angelfish is the size of the tube located between the anal and the ventral fin.
Sexing based on the breeding tube. The female angelfish will expel her eggs and the male angelfish will use external fertilization. Angelfish can not get pregnant.
More fatty and robust bodies. Male angelfish generally grow faster than female ones. This tube will be much thicker in the female than in the male but the difference is generally not easily visible until the fish have begun to spawn.
This could be anywhere in the tank.