Instructions
Preparing for Breeding
Select at least six fish of the species that you wish to breed; this allows them to choose mates as they wish, reducing the chances of complications. Select males that are active, ideally shaped for their breed and brightly colored. Select females that are larger than the males, particularly if the males of the species are aggressive.
Prepare a small "emergency tank" with all the basic requirements for a single specimen of the species being bred, as males may attack females during or after breeding. Make a separate tank for breeding if the behavior of the species requires it -- for example, if other specimens will attempt to eat nested eggs -- this allows you to move the breeding fish into the breeding tank until egg-laying occurs and then return them to the main tank afterward. Use the primary tank as your breeding tank if there are no such complications.
Remove the breeding tank's gravel, if present. Install a filter that has a high rate of water flow and uses a non-cotton filtration system,such as bio-balls, activated charcoal, or sponge filter cartridges. Use an inflow pipe with a sponge on the end to prevent fry from being drawn into the filter.
Ensure that you are not overfeeding your fish. Only feed the fish what they can eat in five minutes.
Clean the breeding tank thoroughly to remove lingering debris, algae and other pollutants; you won't be able to conduct regular cleaning and water changes during breeding and egg-laying.
Behavior-Specific Tank Modifications
Cover the tank bottom with unpainted glass marbles if the species is an egg-scatterer; this will protect the eggs and young fry from being eaten.
Cover the tank bottom in soil substrate if the species uses substrate for egg laying or nest building. Use a specific substrate if the species requires it.
Plant the breeding tank heavily if the species is a livebearer or is prone to eating its fry in captive aquaria. Use additional rocks and other retreat structures if desired.
Encouraging Breeding
Learn if the fish species has a particular breeding season in the wild and encourage breeding during that time period. Learn if the species has any preferred pH or water hardness and replicate the conditions in your tank.
Raise the temperature of the tank to a few degrees above normal. Interact with the tank and fish as little as possible to prevent them from becoming stressed.
Initiate a diet composed primarily of live foods (preferably foods that the fish eat in their natural habitat.)
Monitor the fish for breeding behavior, such as courtship displays, nest building and egg-laying. Watch for overly aggressive behavior and separate the fish if necessary.
Feed the newly-hatched fry with special fry-specific food (as food for adult fish can be inedible or harmful to them.)
How to Breed Fish at Home
The breeding capacity of aquarium fish varies greatly from species to species. Some species breed so readily that you need to take active steps just to stop them; others breed only under very specific conditions; still others have never been seen to breed in captivity. There are principles which must be followed regardless of the species, however; the prospective mates need to enjoy each other's company, they must be strong and healthy enough for the strain of bearing eggs or offspring, and the ensuing infant fish (called fry) must be given safe conditions to protect them until they reach maturity.