By all standards, the Vrljika is a unique karst river, which flows all the way through the Imotski Valley. It is impossible to include it into any standard classification because its hydrological and geological features are the same from the spring to the estuary. In other words, there is no upper, middle or lower flow. It is 23 kilometers long from the spring to the estuary and the whole of its course remains in a valley, just like the course of any other river in a plain. There are five wells at its spring, Jauk, Opačac, Utopišće, Duboka Draga and Dva Oka (or Jezerine), which is a unique phenomenon because the river starts flowing from two completely circular springs not a meter apart. Many legends and stories about the springs fill people with awe for water, which all of us are made of. The Vrljika changes its name along its course: it is called the Matica from Kamenmost on. Finally, the river sinks at the bottom of the valley and reappears in Bosnia and Herzegovina, known as the Tihaljina. The harvest in the Imotski Valley, as well as life itself, depends on the Vrljika. Not long ago the river water was potable throughout its course and endemic species like soft-muzzled trout, spotted minnow and whiteclawed crayfish were swimming in it. Unfortunately, man interfered with the life of the river, convinced that everything is allowed. The rich and fertile strength of the river slowly gives way to the new and cruel times. The area around the spring (and all the way down to the bridge on the river Perinuša) has been protected since 1971 as a special ichthyologic reserve. The river provides the whole Imotski region with fresh water. It is also known to be the habitat for some endemic species of fish, as well as for other fish, which is interesting for European ichthyologists. Although the surface of the reserve is small, the water is of high quality with an abundance of food for the fish. The Vrljika belongs to the Adriatic river basin, the home of 28 endemic species (as opposed to the Danube basin, where there are only two). Two endemic species in the Vrljika have not been studied in full detail yet: soft-muzzled trout (Salmothymus obtusirostris), studied by Krešimir Pažur, Ph.D. from the Faculty of Agriculture in Zagreb, and white-clawed crayfish (Austropotamobius pallipes), whose population is monitored by Goran Klobučar, Ph.D. from the Faculty of Science in Zagreb. It is widely known that white-clawed crayfish and spotted minnow (gaovica) behave as if they were alive (i.e. as if they had just been caught) for several hours after being frozen and defrosted. Although the final conclusion about those endemic species has not been reached yet, the research has been slowed down due to a constant lack of means and protection. Formal and declarative protection has not ensured the survival of the above mentioned animals, so they are still on the list of highly endangered species.