Brown trout reproduce externally — the male and female fish climax simultaneously and release their sperm and eggs into the open water. The event must be timed perfectly, so the female trout indicates she is about to release her eggs by digging a bed in the sand, crouching by it, opening her mouth and quivering. Male fish respond by crouching and quivering beside her. Their quivering intensifies and, about half the time, they both climax. The other half the time, the female quivers, but never releases her eggs.

Brown trout reproduce externally — the male and female fish climax simultaneously and release their sperm and eggs into the open water. The event must be timed perfectly, so the female trout indicates she is about to release her eggs by digging a bed in the sand, crouching by it, opening her mouth and quivering. Male fish respond by crouching and quivering beside her. Their quivering intensifies and, about half the time, they both climax. The other half the time, the female quivers, but never releases her eggs.

Brown trout reproduce externally — the male and female fish climax simultaneously and release their sperm and eggs into the open water. The event must be timed perfectly, so the female trout indicates she is about to release her eggs by digging a bed in the sand, crouching by it, opening her mouth and quivering. Male fish respond by crouching and quivering beside her. Their quivering intensifies and, about half the time, they both climax. The other half the time, the female quivers, but never releases her eggs.