Pelasgus stymphalicus is a threatened species of small freshwater fish. It is a short-lived species, and reaches a maximum length of 12 cm. P. stymphalicus is endemic to slow-flowing rivers and wetlands in the Peloponnese and disjunctly in Lake Stymphalia, a natural eutrophic lake without surface drainage. The main threats to P. stymphalicus are habitat destruction, water extraction and pollution, although the species is resilient and well-adapted to unstable conditions. It is protected under Appendix II of the EU's Habitats Directive (1992) and under Appendix III of the Bern Convention, (1982).