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Yes, but it's very hard to get fish to use them. Some species are almost completely blocked even if there is a ladder.

They don't work for many species. For example, one study found that 3% of American shad were able to use a fish ladder. https://e360.yale.edu/features/blocked_migration_fish_ladder...

Fish ladders are akin to greenwashing.

Fish ladders are expensive and have a fairly large negative impact on yearly electric output. Forcing upgrades makes most dams too expensive, which would mean they get replaced by fossil fueled power plants which can more cheaply operate as backup for wind and solar.

As a result, most hydro power in Europe is in direct violation of environmental laws, but are also given exceptions given the yearly and regular energy crisis.