Studies were carried out on the growth of Chromatium sp. on seafood wastewater (SFWW), which under facultative conditions and light exposure produced red pigment. The strain grew and utilized organic matter in both dark and light exposure conditions, but it produced red pigment when exposed to light. The growth was repressed by aerobic condition. The red color intensity was reduced by about 32.5 +/- 1.5 and 70.8 +/- 2.8% when kept under dark and static conditions, or aerobic and light exposure conditions, respectively. The COD of SFWW and the number of cells of Chromatium sp. were also rapidly reduced by about 78.6 +/- 2.7 and 92.0 +/- 1.0%, respectively, under aerobic and light exposure condition. KNO3 and FeCl3 also reduced red color intensity and maximum removal of organic matter and red color were 30 and 4 mg/l, respectively. Aerobic conditions increased the color removal efficiency with 30 mg/l KNO3 and 4 mg/l FeCl3 treatments up to 96.5 +/- 1 and 98.9 +/- 1%, respectively. (c) 2005 Elsevier Ltd. All rights reserved.