Abstract— The growth experiment of seaweed using cage system was conducted in Semporna, Sabah under the metrological condition in Malaysia. The experiment was conduct from September until May 2013. Seaweeds were cultivated on floating cage near of mussel farms. Salinity ranged from 29 to 36 psu and temperature from 28.5 to 32.5°C. Present study of the seaweed Kappaphycus Striatum var. Sacol aims to determine the growth rate of five different densities cultured in a cage of 9 meter 2 . There were 4 kg cage -1 , 20kg cage -1 , 40 kg cage -1 , 60 kg cage -1 , and 80 kg cage -1 . The densities had been distributed into a cage by using 3 meter length line containing 20 points for seedling attachment. The 4 kg cage -1 contains 1 line in a cage, 20 kg cage -1 contain 5 lines in a cage, 40 kg cage -1 contain 10 lines in a cage, 60 kg cage -1 contain 15 lines in a cage, and 80 kg cage -1 contain 20 lines in a cage. Growth rate are varied between five different densities studied. The density of 40 kg cage -1 (percentage daily growth rate, 1.39±0.31) were identified as effective density. Higher growth rates (2.8-3.5% day −1 ) were measured in day 35, showing a positive correlation between growth rate and water temperature. Line 5 could be practice on commercial cultivation of Kappaphycus Striatum var. Sacol in a cage. Keywords—Cage Culture; Daily Growth Rate; Density; Kappaphycus Striatum. I. INTRODUCTION EAWEED becomes one of important agricultural crop in Malaysia that really concern by the government. It is proven by the government allocation RM 58.87M for year of 2011 and 2012 and more money being invested in this year to boost more this sector [16]. Moreover, there is a lot of strategies and incentives be taken under Third Economic Transformation Programme (3ETP). Such us strategies are Algae Farming via Mini Estate System in Sabah [18], Seaweed Identification Grant, Seaweed Cultivation Grant and Grant from National Key Economic Area (NKEA). The demand of carrageenan is increasing worldwide but there is insufficient supply of dried seaweeds in the market. (Ask and Azanza, 2002; Pickering et al. 2007; Castelar et al. 2009; Bixler and Porse, 2011). ). Rhodophyta divisions contain the M.K. M Ali is with the Mathematics with Economics Programme, School of Science & Technology, Universiti Malaysia Sabah, Kota Kinabalu, Malaysia (corresponding author’s phone:+60149543405). S. Md. Yasir was with Seaweed Research Unit (UPRL), School of Science and Technology, Universiti Malaysia Sabah, Jalan UMS, 88400 Kota Kinabalu, Sabah, Malaysia. largest amount of amorphous embedding matrix polysaccharides as in fig. 1, whereas fig. 2 shows the Morphology Kappaphycus Striatum variaty Sacol. This characteristic, combined with their well known ability to bind metals, makes them potentially excellent heavy metal biosorbents (Majid et al; 2013). Fig. 1 Cell wall structure in the red algae (Volesky, 2003) Fig. 2 Morphology Kappaphycus Striatum variety Sacol (Majid khan et al., 2013) The production of Kappaphycus (cottoni) in Malaysia, mostly at Sabah contributes to only 2.5% (4,000 tonnes dry weight) in total world production of Kappaphycus (cottoni) at 2006 (Hurtado, 2007). The cultivation of Kappaphycus Striatum variety Sacol by fixed long line and fixed bottom line which had been long practiced by the local people at Sabah is exposed to predators such as turtles and fishes. The attack from the predators could greatly decrease the production of the seaweeds. In order to reduce the risk of that matter, the cage culture had been introduced for cultivating the Kappaphycus Striatum variety Sacol at Semporna, Sabah. The use of cage had been practiced by other researchers and proven as significantly effective as long line or bottom line (Hurtado- Ponce, 1992; Dawes et al. 1994; Gerung and Ohno, 1997; Paula et al. 2002; Bulboa and Paula, 2005; Msuya and Kyewalyanga, 2006; Hayashi et al. 2007). The present study was carried out to investigate the optimum density of seedlings could be cultured at a cage of 9 meter 2 and stocking density of 100 gram per seedling. Besides, Improvement of Growth and Mass of Kappaphycus Striatum var. Sacol by Using Plant Density Study at Selakan Island in Semporna Malaysia M.K. M Ali, J.V.H. Wong, J. Sulaiman, J. L. Juli, and S. Md. Yasir S International Conference on Biological, Chemical and Environmental Sciences (BCES-2014) June 14-15, 2014 Penang (Malaysia) http://dx.doi.org/10.15242/IICBE.C614020 58