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. It can be distinguished most easily from the European or broad-fingered crayfish (Astacus astacus) by the relatively thinner "fingers" of the claws.
The Astacus leptodactylus can grow up to 30cm (1 foot) in length from the tip of the rostrum to the end of the telson (tail). But is more commonly found at around 15 cm in length. The sides of the thorax are very rough, usually paly yellow to pale green in colour. Has two pairs of post-orbital ridges; second row may have spines. also has a prominent tubercle (small nodule) on shoulder of the carapace. The claws of the Astacus leptodactylus are long and narrow (hence the common name 'Narrow clawed crayfish'). Their upper surface is rough and the underside is the same colour as the body. Also one tubercle can be found on the fixed side of the claw.
The Astacus leptodactylus is fairly docile, especially the male with large claws. Astacus leptodactylus favour relatively still water as in lakes and canals.