Astacus leptodactylus, the "Danube crayfish", "Galician crayfish", "Turkish crayfish" or "narrow-clawed crayfish", is a species of crayfish imported and introduced to Central Europe in 19th century from the Caspian Sea region.
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Astacus pachypus, the "Caspian crayfish", is a species of crayfish found in the Caspian Sea, the Don river, and parts of the Black Sea and Sea of Azov, where it lives in salinities of up to 14‰.
Astacins are a family of digestive enzymes, discovered in the 1990s, which were first isolated from Astacus astacus.
The fish is endangered, because various competitors were introduced into the lake during the Soviet period, including common whitefish (Coregonus lavaretus) from Lake Ladoga, goldfish (Carassius auratus) and narrow-clawed crayfish (Astacus leptodactylus); and because of lake level change.
Many crustaceans like crabs (Scylla spp., Portunus spp.), spiny lobsters (Panulirus spp.), crayfish (Astacus spp., Cherax spp.) and freshwater shrimp (Macrobrachium spp.) are reported to be infected with variable severities depending on the life stage of the host and presence of external stressors (temperature, salinity, bacterial diseases, pollutants).