Instructions
Gather several angelfish in the same tank. Make sure that the tank is at the ideal temperature and cleanliness to promote health. The best way to determine the sex of an angelfish is by examining a group while they are spawning. This is easiest when you have several fish in the tank to increase the probability that both sexes will be present and will eventually pair off to mate.
Identify spawning preparation. Spawning can be identified when you see two fish preparing a site for laying eggs by cleaning it and making special runs over the site to practice for the deposit. This could be a rock or a leaf inside the tank that will be a safe place for the angelfish to lay their eggs.
Examine the ovipositors of the different fish. Ovipositor means "egg-depositor" and they are the sexual organs that are present on both male and female. They are ovipositors on female angelfish are larger and more blunt as opposed to male ovipositors which are more slender, longer and pointed. This tube like structure is located between the anal fin and the ventral fin at the bottom rear of the fish.
Watch the angelfish closely over the course of two to three days. The female will pass over the spawning site several times through the preparation period and eventually deposit the eggs. The male will follow to fertilize the eggs. This process will continue until the pair deposit and fertilize hundreds of eggs.
How to Distinguish Between Male & Female Angelfish
Gauging the gender of an animal is generally not too difficult, but fish sex organs are much different than other animals. A fish's sex organs are only exposed during spawning and are not external, as are those of mammals. The only foolproof way to distinguish a male angelfish from a female is to wait until they pair up and prepare to lay and fertilize their eggs.