Stechlin Cisco

Coregonus fontanae is highly dwarfed, and is believed to be the world's smallest type of cisco. The maximum length recorded for this species is 12.6 centimetres (5.0 in), and 10 centimetres (3.9 in) is believed to be a typical size. Stechlin ciscoes are silvery pink in body color, with a bluish-brown back and glassy fins. The Stechlin cisco is taxonomically distinguished from the vendace and the other dwarfed cisco species by its low number of lateral line scales (69–77), by some bodily proportions, by the length of its gill rakers, by its slow growth, by its glassy fins, and by its spring spawning season.

This species is restricted to the Großer Stechlinsee (also called Lake Stechlin), near the town of Stechlin in the north of Brandenburg state in Germany. Lake Stechlin is a deep, cool, chalky, oligotrophic lake of recent glacial origin. Lake Stechlin has an area of 4.3 square kilometres (1.7 sq mi) and reaches a maximum depth of 68 metres (223 ft) and a mean depth of 22.8 metres (75 ft). In Lake Stechlin, this species and the vendace (Coregonus albula) make up 95 percent of the fish biomass. Lake Stechlin is part of Stechlin-Ruppiner Land Nature Park. The IUCN Red List considers the species to be Critically Endangered.

Stechlin ciscoes feed primarily on cladocerans and copepods. They are found throughout the lake, though they are generally pelagic in cool, deep water. They differ little in dietary preferences from the sympatric vendace, but they differ substantially in habitat. They live to be four to five years old, and spawn in the spring, unlike the vendace. They have been found to have a reduced metabolic rate as an adaptation to their habitat.