Mar, Fresh. Behav. Physio!., Vol. 31, pp. 115-121 Reprints available directly from the publisher Photocopying permitted by license only © 1998 OPA (Overseas Publishers Association) Amsterdam B.V. Published under license under the Gordon and Breach Science Publishers imprint. Printed in India. Short Communication DIFFERENCE IN SHOALING BEHAVIOUR BETWEEN OCELLATED (SYMPHODUS OCELLATUS) AND LONG-STRIPED (S. TINCA) WRASSES AND ITS RELATION TO OTHER BEHAVIOURAL PATTERNS S.V. BUDAEV* and D.D. ZWORYKIN A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 33 Leninsky prospekt, 117071 Moscow, Russia (Received 6 February 1997; Revised 27 May 1997; In final form 10 June 1997) Keywords: Symphodus ocellatus; Symphodus tinca;shoaling; body size; foraging; activity Shoaling behaviour in fishes is acknowledged as an important adaptive mechanism (Radakov, 1972; Magurran, 1990; Pitcher and Parrish, 1993), and its benefit as a defence against predators is particularly well docu- mented (see Magurran, 1990, for a review). However, as in other behav- ioural strategies, shoaling may have associated costs, namely increased competition for limited resources and, possibly, manipulation by con- specifics (Pitcher and Parrish, 1993; Metcalfe and Thomson, 1995). In the present article we document differences in shoaling behaviour between two species of wrasses ( Symphodus genus, Teleostei: Labridae) - ocellated, S. ocellatus Forskål and long-striped, S. tinca (L.). These fishes are common inhabitants of shallow waters throughout the Black Sea. Both maintain territories only during the reproductive period (Mochek, 1987), * Corresponding author. E-mail: sevin@glas.apc.org. 115