Conditioning
From The Aquarium Wiki
This refers to the husbandry of the animal to bring it into prime health and therefore into a state ready for breeding.
This entails keeping the water in excellent condition, feeding the animal (usually live food) especially well and ensuring its in a stress free environment.
Occasionally depending on the species, there may be required a change to its environment to kick start it into a breeding state. For example: Lowering or increasing the temperature or lowering the level of the water briefly.