Tied as fundamental instruments in the highly specialized short line nymphing technique, Czech nymphs can be as imitative or as attractive as one desires. Key aspects of the nymphs are that they get tied on Gammarus (i.e. scud, caddis) hooks, are weighted, and are slim in nature. Typically Czech nymphs have a shellback to assist in cutting depth detracting surface area and to boost their natural appearance as well as a flashy under rib. It's important to realize that Europeans fish heavily for grayling in rivers where caddis are the prevalent food item. Grayling do not mind heavy flows and are attracted to bits of flash and color. It is not necessarily counter effective to fish outlandish patterns for trout, but it is wise to carry more imitative selection if trout are your primary focus.