Breeding aquarium fish is not as difficult as you might think. If you have been keeping fish for a while, then you are probably ready to step into the world of breeding fish. In order to get fish to spawn, the aquarium owner must first be able to tell the male fish from the female fish, and then identify the type of breeding the fish use.
Some fish species are easier to determine the sex of than others. In fish with obvious differences, the sexes can be distinguished by color differences, fin differences, and the shape of sexual organs. If the difference is in the color, the male will be the brighter, more colorful fish of the pair. Some fish species are isomorphic, which means there are no visible differences between the sexes. In these fish, it is often only when they choose to spawn that you can tell the males from the females.
When choosing your breeding pair, look for fish that are good specimens of the species, as they will create the most attractive babies. Also, choose only fish that are fully-grown and healthy. Research the species you wish to breed, as some will not breed unless they have lived in a community tank together for a long period of time. Try to avoid crossing different color strains of the same variety. Chances are you will get young in an unattractive color variety.
Egg-laying fish are divided into five different groups, depending on the way they lay their eggs. The first group is the egg scatterers. These fish simply spawn their eggs and allow them to land where they fall. They do not care for their young. Egg scatterers often spawn in a school, and they lay a huge number of eggs. The young, which are called fry, hatch quickly, and if the parent fish are not removed, they will eat the fry.
Egg depositors are another group of egg laying fish. There are egg depositors that care for their young, and egg depositors that do not. Each species of egg depositor will have a different place that they choose to deposit their eggs. It might be inside a cavity, such as a flowerpot, or on an open surface, such as a piece of glass. The fish that care for their fry will guard the eggs and the babies until they can fend for themselves.
Egg burriers are a very interesting type of fish to attempt to breed. These are fish that come from areas where portions of their habitat dry up for some significant portion of the year. They will actually leave the water to burry their eggs in the exposed mud. In order to breed these types of fish, you will have to have a set up that allows the parent fish to leave the water and burry their eggs.
Mouth brooders are an interesting fish to observe. They keep their eggs and babies in their mouths until they can care for themselves. They do not eat their young, but rather protect them inside their mouths until they can fend for themselves.
The final category of egg laying fish is the nest-builders. Nest-builders put their eggs into some sort of nest that they build. Usually these are bubble nests formed with saliva-coated bubbles. Sometimes fish will dig pits into the substrate to lay their eggs in. These fish care for their young after they hatch.