A fish-passable barrier to stop the invasion of non-indigenous crayfish

► Indigenous crayfish are in great danger due to invading non-native signal crayfish. ► The invasion of non-native crayfish can be stopped by physical barriers. ► A new physical crayfish barrier was developed that allows fish migration. ► Barrier efficiency depends on barrier roughness, barrier slope and flow velocity. ► Signal crayfish can breach barriers by swimming backward.