Crayfish can spend their whole life, including reproduction and development, in fresh water. It is considered that many advanced features, like direct development and maternal brood care, can be interpreted as adaptations to life in fresh water (Scholtz, 1995). However, crayfish may also be found in environments that are subject to variations in salinity (Holdich et al., 1997). P?queux (1995) stated that, although under natural conditions most crayfish have adapted to a stenohaline way of life, they may survive to some degree in experimentally increased salinity. Cherkasina (1975) reported that Astacus leptodactylus Eschscholtz, 1823 and Astacus pachypus (Rathke, 1837) live in waters of up to 14 ppt salinity in the Caspian Sea. A. leptodactylus, the only crayfish native to Turkish waters, is known from estuarine environments. K?ksal (1988) also reported A. leptodactylus from the Black Sea. Various studies have been conducted on determining the salinity tolerance of a number of crayfish species through survival and growth trials (McMahon, 1986; Austin, 1995; Holdich et al., 1997; Susanto & Charmantier, 2000). Holdich et al. (1997) have shown that juveniles and adults of A. leptodactylus are well adapted to survive in salinities of at least 21 ppt in the long term, and to being transferred directly back into fresh water. However, some researchers state that their ability to colonize the estuarine environment may be restricted to areas of low salinity (Susanto & Charmantier, 2000) due to the adverse effects of sea water on egg development and hatching. Hence, consideration of a brackish-water environment may be more realistic. The ability of A. leptodactylus to grow at relatively high salinities opens up the opportunity of culturing this species in brackish water and also provides the op