How to Know If a Fish Is In Trouble

How to Know If a Fish Is In Trouble

There are tells that will show you when almost any fish, from the cold river to the ocean, is significantly stressed to the point that it may not survive. These fish need extra TLC to be revived.

But it’s important not to get in the habit of trying to revive every fish that doesn’t need it–in those cases, you’re overhandling a fish that would be fine if you just let it swim away. If you go to Keep Fish Wet, you’ll find a wealth of science-based information on best catch-and-release practices. It’s also worth reading our Flylab primer on handling fish, particularly when it’s hot: Fish Handling 101.

So, how do you know when a trout you catch needs extra help, like pointing it upstream in the current to get water (and oxygen) flowing through its gills? Dr. Andy Danylchuk showed me a number of things, but three signs really stuck out:

1. If a fish can swim away on its own, let it. If you’re gently gripping it by the tail, and it wiggles as if to swim away, that’s good. If it just sits there, it might need help.

2. If you tilt a fish back and forth, its eye should roll, almost tracking you. If its eyes demonstrate a blank, fixed stare without movement, that’s a problem.

3. If the trout cannot right itself if you roll it on its side, within three seconds, that’s another problem.

If those things happen, you might go into revival mode, keeping the fish in the water in your rubberized net, facing into the gentle current, still handling with wet hands as little and as softly as possible. And when they do want to swim away, let them do it.

Best practices for catch-and-release: