The first cavefish in the Dinaric Karst?

Telestes karsticus is a fish that lives in Sušik stream and Sušik cave near Ogulin, Croatia. Not only the species has been recorded in the cave year-round, T. karsticus also reproduces in the cave! This represents the first record of a fish spawning in a Dinaric Karst.

Here you can find more details, such as what happens when surface fish is exposed to total darkness and cavefish to daily light/dark cycle.