Effects of dietary fish oil replacement with vegetable oils on growth and tissue fatty acid composition of humpback grouper, Cromileptes altivelis (Valenciennes) Rossita Shapawi 1 , Saleem Mustafa 1 & Wing-Keong Ng 2 1 Borneo Marine Research Institute, Universiti Malaysia Sabah, Sabah, Malaysia 2 Fish Nutrition Laboratory, School of Biological Sciences, Universiti Sains Malaysia, Penang, Malaysia Correspondence: R Shapawi, Borneo Marine Research Institute, Universiti Malaysia Sabah, Locked Bag 2073, 88999 Kota Kinabalu, Sabah, Malaysia. E-mail: rossita@ums.edu.my Abstract The replacement of dietary marine ¢sh oil with vegetable oils was examined in ¢ngerling humpback grouper, Cromileptes altivelis , over the course of an 8- week growth trial. Five isolipidic (10%) and isoproteic (50%) ¢sh meal-based practical diets were formu- lated to contain iso-ingredients but with di¡erent sources of lipids [crude palm oil (CPO), re¢ned, bleached and deodorized, palm olein (RBDPO), soy- bean oil (SBO) or canola oil (CNO)], and their perfor- mance was compared with the control diet, which contained cod liver oil (CLO) as the added lipid source. The experimental diets were fed close to ap- parent satiation twice a day to triplicate groups of ¢sh (10.6  2.2 g). The grouper ¢ngerlings were ran- domly distributed into groups of12 ¢sh in cylindrical cages (61cm depth and 43 cm diameter) that were placed in a 150tonne polyethylene seawater tank. There were no signi¢cant di¡erences ( P40.05) in terms of growth, survival, feed conversion ratio, pro- tein e⁄ciency ratio, net protein utilization, hepatoso- matic index and condition factor among ¢sh fed the various dietary treatments. Similarly, the dietary lipid source did not signi¢cantly a¡ect the whole body proximate composition of the ¢sh. Muscle and liver fatty acid composition of ¢sh was in£uenced by the experimental diets. Replacement of dietary CLO with CPO, RBDPO, SBO or CNO produced ¢sh with lower n-3 highly unsaturated fatty acids and increased levels of 18:2n-6 in the muscle and liver. The n-3:n-6 fatty acid ratio in the muscle of ¢sh fed the CLO-based diet was 3.0 compared with 0.5^0.8 inthe muscle of ¢sh fed the various vegetable oil-based diets. The present study demonstrated that various vegetable oils can be used in ¢sh meal-based dietary formula- tions for humpback grouper without compromising growth or feed utilization e⁄ciency. Keywords: grouper, pelleted feed, plant oils, growth, fatty acids Introduction The humpback grouper, Cromileptes altivelis (Valen- ciennes), is a high-priced species in the live reef ¢sh trade in Southeast Asia. They are heavily exploited in its natural habitat and are listed in the World Conservation Union (IUCN) red list of threatened species. In recent years, there has been increasing interest in the commercial culture of various grouper species, including the humpback grouper, especially in Taiwan, Indonesia, Thailand and Malaysia. The regional total production of groupers through aquaculture in 2001 had been estimated to be more than 23000tonne and valued at around US$160 million (Rimmer 2004). The farming of these carnivorous tropical marine ¢sh is heavily dependent on the use of trash ¢sh. The rapid expansion of grouper culture in the Asia-Paci¢c region and the projected limited availability of trash ¢sh had encour- aged more ¢sh farmers to use commercial pelleted feeds so as to sustain the development of this indus- try (Boonyaratpalin 1997; Rimmer 2004; Williams, Smith, Williams, Irvin & Barclay 2005). However, very limited information is currently available on the nutrient requirements of the humpback grouper. Aquaculture Research, 2008, 39, 315^323 doi: 10.1111/j.1365-2109.2007.01882.x r 2008 The Authors Journal Compilation r 2008 Blackwell Publishing Ltd 315