Spatial analysis of water quality and its suitability in farming giant freshwater prawn (Macrobrachium rosenbergii) in Negeri Sembilan region, Peninsular Malaysia Benjamin Ezekiel Bwadi, 1,2 Firuza Begham Mustafa, 1 Mohammad Lokman Ali 3,4 and Subha Bhassu 3 1 Department of Geography, University of Malaya, Malaysia 2 Department of Geography, Taraba State University Jalingo, Nigeria 3 Institute of Biological Science, Division of Genetics and Molecular Biology and Centre of Biotechnology for Agriculture, CEBAR, University of Malaya, Malaysia 4 Department of Aquaculture, Patuakhali Science and Technology University, Bangladesh Correspondence: Benjamin Ezekiel Bwadi (email: bwadiben@gmail.com) Finding potential sites for resilient prawn production in the tropical environment that also pre- vents wastage of natural resources is not an easy task. The purpose of this study is to evaluate water quality suitability for prawn farming in Negeri Sembilan of Peninsular Malaysia based on Geographic Information System (GIS). To achieve this goal, numerous criteria including sources of water, water temperature, water pH, sources of pollution, salinity, soil texture and availability of phytoplankton criteria were considered for the modelling process. Analytic Hierarchy Process (AHP) technique was performed to standardize the criteria and the weighting process. The weighted overlay of indicators and results were accomplished by applying the Multi-Criteria Deci- sion Analysis (MCDA) method in GIS. It was indicated that the Negeri Sembilan area has potential for prawn farming. The results showed that about 25 per cent (163 056.93 ha) of the area was most suitable for prawn farming, about 58 per cent (384 656.88 ha) was considered moderately suitable, while 18 per cent (117 633.49 ha) was regarded as least suitable. The study concluded that the multi-criteria decision analysis of water quality for prawn farming is vital for regional eco- nomic planning in the Negeri Sembilan area and also significant when establishing a model for aquaculture development. Keywords: Analytic Hierarchy Process, giant freshwater prawn farming, suitability evaluation, spatial analysis, water quality, Negeri Sembilan of Peninsular Malaysia Accepted: 2 February 2018 Introduction The quality of water is fundamental to the growth and survival of cultured giant fresh- water prawn (Macrobrachium rosenbergii). Groundwater and surface water are the two main categories of water supply for any aquaculture practice. However, not all avail- able water is suitable for giant freshwater farming. In the early stages of growth, fresh- water prawns require salty water along the estuary and close to the coast for its survival. However, as it grows into maturity, the prawns migrate into freshwater of favourable quality (New, 2008). Water quality varies significantly from one place to another due to different environmental conditions and human usage. The giant freshwater prawn (Macrobrachium rosenbergii) is also known as Udang galah in Malay. It is a species of crustacean distributed in most parts of the tropical countries of the world and is known for its big size and rich taste (New & Kutty, 2010). Owing to favourable conditions, the species is mostly cultivated in South-East Asia and South and North America. By 2007, China and India had produced more than half of Singapore Journal of Tropical Geography (2018) © 2018 Department of Geography, National University of Singapore and John Wiley & Sons Australia, Ltd doi:10.1111/sjtg.12250