Obviously designed for trout on the Bighorn River in WY and MT.Meant to mimic a dead or spawning scud, making it work well in a dead drift, and also on the swing.While intended to be fished on a river (where current more dictates its movement), it has been known to be effective in lakes especially during spawns.On rivers fish in slower areas and spots with a lot of weeds (areas scuds like to be), on lakes fish with a sinking line and retrieve slowly.