Spawning Tropical Fish

Spawning Aquarium fish is easy in many cases.
Just follow these simple procedures: female angelfish with eggs
Make sure you have a real pair
Make sure the breeders are in the best of health
Condition the breeders on good food
Have clean water of the proper pH and hardness for the particular species
Provide for their special needs, such as caves or spawning mops or spawning grates etc
Disturb the pair as little as possible

And there you have it as far as basics go, please see the individual fish articles for specific details for particular species.