World-wide, fish passes are constructed to assist the migration of salmon and trout across upstream weirs. They generally include any cascade that serves as a bypass to a weir, as these species are excellent swimmers and jumpers, and migrating upstream they can even jump over small weirs. In European countries the range of migrating fish species is more diverse. Some of them don’t even swim, as such, and just crawl along the bottom of the river instead. Others are weak swimmers and some of them need to have multiple rests when going through a fish ladder.

Additionally, fish pass design and realization in the Czech republic and other European countries must conform with many strict requirements, such as max / min velocity, depth, locations with standing water for fish to rest in, a special track for eels etc., and must also service downstream migration as a fish-friendly bypass.