Journal of Agricultural, Biological and Environmental Sciences | Year-2017 | Volume 04 | Pages 13-27 © 2017 Jakraya JOURNAL OF AGRICULTURAL, BIOLOGICAL AND ENVIRONMENTAL SCIENCES Journal homepage: www.jakraya.com/journal/jabes ORIGINAL ARTICLE Water Quality Assessment in Selected Aquaculture Sites in Brunei Darussalam Anthony Banyouko Ndah 1 , Gabriel Yit Vui Yong 2 , Umar Abdul Aziz Bin Yahya 3 , Asyraf Mohammad Bin Haji Arine 4 , Nasrullah Muhammad Bin Murni 5 and John Onu Odihi 6 12345 Department of Geography, Development and Environment Studies, Faculty of Arts and Social Science, Universiti Brunei Darussalam, 6 Department of Geography, University of Maiduguri, Borno State, Nigeria. *Corresponding Author: Anthony Banyouko Ndah Email: tonyban83@163.com Received: 20/03/2017 Accepted: 09/04/2017 Abstract Efforts are currently underway to boost aquaculture production in Brunei Darussalam. However, since aquaculture is a space-based activity, understanding environmental parameters and maintaining environmental/water quality are vital for this goal to be achieved. This research therefore aims to determine the state of environmental quality in aquaculture sites in Brunei based on two methods: 1. Laboratory analysis of water samples collected from aquaculture sites and environs over the course of a week (29 th Oct. to 6 th Nov. 2014); 2. Qualitative approach based on interviews with officials at the aquaculture section of the Department of Fisheries and with individual aquaculture operators. The results reveal the following: across all the study sites, a few water quality parameters were found to be within normal or acceptable levels, including: biological oxygen demand (BOD), total suspended solids (TSS), turbidity and pH and oil and grease residues. Total Alkalinity falls below the optimal level while nutrients (phosphate, nitrite and ammonia) exceed the maximum acceptable levels especially at Hazmi and Helif aquaculture. Helif in particular has been found to be plagued by numerous environmental problems, including extremely low levels of alkalinity, enhanced water colour and eutrophication. Ammonia and Chlorine concentration are found to significantly exceed recommended levels across all sites indicating a potential for ammonia toxicity while high chlorine concentrations has been linked to the misapplication of chlorine in efforts to combat white spot disease (WSD). On the bases of these results, this study recommends stringent implementation of Environmental Impact Assessments, respect of environmental quality standards and regular monitoring/evaluation prior to and during ongoing aquaculture operations. Keywords: Aquaculture, Environment, Water quality assessment, Brunei Darussalam. 1. Introduction Aquaculture is commonly defined as the high- density production of fish, shellfish, molluscs, crustaceans and plant forms which aims to enhance production by regular stocking, feeding and protection from predators in a controlled environment using open and/or close systems, in which stocking rates are typically many folds greater than wild environments (Larsson, 1994). Aquaculture production has increased worldwide; accordingly the use of aquafeeds has increased tremendously (Rahmatullah and Rahmatullah, 2015). In Brunei Darussalam, agriculture, fishing and forestry used to be the major economic contributors until the 1920s when oil and gas resources were first discovered (Kurus et al., 2002) and the country’s economy has been almost entirely dependent on fossil fuel production ever since. However, seafood has been one of the principal sources of protein for the people of Brunei Darussalam. The demand for sea food in Brunei is very high, and projected to grow at 3.6% annually (Statistics Division, Economic Planning Unit, Ministry of Finance, 1993). With the agriculture and Fisheries sector contributing only 1% of the GDP (Sulaiman, 2000), consequently, the country imports approximately 50-60% of its fishery needs to meet local demand. To satisfy local consumption as well as reduce the dependence on imports, the government of Brunei via its Department of Fisheries (DOF)