Effects of temperature on survival and growth of juvenile spinefoot rabbitfish (Siganus rivulatus) Imad Patrick Saoud 1 , Chadi Mohanna 2 & Joly Ghanawi 1 1 Department of Biology, American University of Beirut, Beirut, Lebanon 2 Institute of Oceanography and Fisheries, Ministry of Agriculture, Batroun, Lebanon Correspondence: I P Saoud, Department of Biology, American University of Beirut, Bliss Street, Beirut, Lebanon. E-mail: is08@ aub.edu.lb Abstract Interest in culturing marbled spinefoot rabbit¢sh Siganus rivulatus is increasing in countries on the Eastern Mediterranean, Red Sea and Arabian Gulf. However, information on environmental tolerances and requirements for optimal growth are scarce. In the present work, the temperature requirements for spinefoot rabbit¢sh were investigated in two experi- ments. In the ¢rst experiment, juvenile rabbit¢sh were distributed into eight 180 L square tanks at 12 ¢sh per tank. The temperature in four tanks was re- duced at a rate of 1 1 C day 1 and in four tanks was increased by 1 1 C day 1 until the ¢sh stopped feed- ing. Minimum and maximum temperatures for feed- ing were recorded. In the second experiment, the ¢sh were placed in four temperature treatments (17, 22, 27, 32 1C) at four replicates per treatment for 8 weeks. Survival and growth were evaluated. Fish stopped feeding at 14 and 36 1C. Their maximum growth rate was at 27 1C, and survival was 100% in all treat- ments. The relationship between speci¢c growth rate and temperature was parabolic, described by the equation: SGR 5  0.0014 ( T 3 )10.0798 ( T 2 )  1.3089 ( T)16.7342. The results show that S. rivulatus is a eur- ythermal ¢sh whose optimal temperature for growth is circa 27 1C. Keywords: Siganus rivulatus , rabbit¢sh, temperature Introduction The marbled spinefoot rabbit¢sh Siganus rivulatus is a euryhaline herbivorous ¢sh distributed in the Indo-West Paci¢c region (Woodland1983). It is one of the most successful Lessepsian migrants, having es- tablished itself along the eastern Mediterranean coast since the opening of the Suez Canal in 1869 (Por 1978). Presently, there is a good market for ¢sh in Eastern Mediterranean countries, and rabbit¢sh is even becoming important in Greek ¢sheries (Papa- constantinou 1990). Moreover, interest in the aqua- culture of ¢sh is increasing as evident from recent publications (El-Sayed, Mostafa, Mohammadi, Dohai- mi & Kayid 1993; Osman, Yousif, Anwahi & Cherian 1996; Yousif, Osman, Anwahi & Cherian 1996; El^Dakar 1999; Stephanou & Georgiou 1999; Saoud, Kreydiyyeh, Shalfoun & Fakih 2007). Siganids are ea- sily reared and have commercial importance for ¢sh- ery production (Juario, Duray, Duray, Nacario & Almendras1985; Hara, Kohno & Taki1986). However, little is known of the environmental tolerances of the marbled spinefoot. The growth rate of ¢sh is a¡ected by several biotic and abiotic factors (Brett & Groves1979), of which temperature is very important (Fry 1971; Somero, Dahlho¡ & Lin 1996). Ambient water temperature regulates growth rate by a¡ecting many physiologi- cal processes in ¢sh (Brett 1979; Jobling 1996) such as food consumption, metabolic rate, reproduction, activity and survival (Jobling 1994; Hillman, Miller & Nishitani 1999). Furthermore, ¢sh are more sus- ceptible to disease at extreme temperatures (Holt, Sanders, Fryer & Pilcher 1975). Provided that food availability is unrestricted, metabolic rate increases as temperature increases. Growth is found to decrease at temperatures above the optimum because of a pos- sible decrease in appetite and high energy cost of maintenance metabolism (Xiao-Jun & Ruyung 1992; Jobling 1994). At low temperatures, growth is Aquaculture Research, 2008, 39, 491^497 doi: 10.1111/j.1365-2109.2007.01903.x r 2008 The Authors Journal Compilation r 2008 Blackwell Publishing Ltd 491