Noone is going to be able to give you an answer on this because every species of fish is different in what they do. Without giving the species of fish you have, sorry noone can tell you anything. You have egg layers, and live bearers, and bubble nest builders and mouth brooders etc…

This is hard because you cant really tell when fish are mating. They usually do chase each other around like “foreplay” It is hard to tell any way