Beavers are busy indeed, but not eating fish: they are strict vegetarians. Their tails are good for many things, but not propulsion. Beavers do not harm fish. You’re thinking of an otter ripping into a struggling trout.
The truth about beavers

Beavers are busy indeed, but not eating fish: they are strict vegetarians. Their tails are good for many things, but not propulsion. Beavers do not harm fish. You’re thinking of an otter ripping into a struggling trout.