The fish that lay their eggs in the open are often of the monogamous persuasion. Though they lay their eggs in the open, they need a smooth surface in order for their eggs to stay in place. If you are preparing an aquarium for these fish to deliver fry, be sure to include smooth rocks and pieces of wood. Sometimes these fish might lay their eggs on the glass side of the aquarium. Because of their monogamous tendencies, it may be difficult to get two of these unfamiliar fish to mate. In addition to their loyalty to their mate, these fish are very protective of their eggs and their fry. You may notice them moving their eggs around the aquarium. They will also take their fry into their mouths to move them out of danger.

Other substrate egg layers hide their eggs away from human and predator sight. These fish are not as partner oriented as the open substrate egg layers. The female in this pair goes into hiding as she finds a place for her eggs. She then stays out of sight, watching over her eggs until they hatch. Because it is difficult to tell whether or not eggs have been laid and fertilized, it is best to keep the male with the female until the eggs hatch. Once the fry are born, remove the male from the delivery aquarium. However the female often needs to stay with her young fry for a month before they can be separated.

It is important to understand the differences between egg laying fish, especially if you hope to breed your fish. Looking into the lives of fish gives humans a valuable view into the mysterious workings of nature and life in general.