fishtrap

2. A narrow passage or enclosure in a river designed to funnel fish into a catching area.

The villagers built a fishtrap across the shallow stream.

3. A device or structure used to trap or confine fish for study or breeding.

Researchers placed a fishtrap in the pond to count the young salmon.

4. Informal: a tricky situation that is hard to escape, like a fish caught in a trap.

The narrow hallway felt like a fishtrap during the crowded sale.