Let’s put it this way: you’ll know if their breeding or not. Normally, they’ll swim lazily about, not disturbing each other or the water. Suddenly, the fish are ganging up on each other, pushing, jumping, flailing, and being more active than ever.
It also may smell a little weird… Looks like it’s spawning season! It normally happens around May or June, but it can differ depending on the area. If this isn’t the pond fish behavior you’re experiencing, keep reading for other reasons.