Both these compounds are toxic for shrimp
(Rao et al., 2000; Antony and Philip, 2006); this means that
they should be controlled at levels that are safe for shrimp
growth. Among the microbes associated with the carbon,
nitrogen and sulfur cycles, of shrimp ponds, purple nonsulfur
bacteria (PNSB) are probably the most useful to improve the
water quality during shrimp cultivation (Antony and Philip,
2006; Zhou et al., 2009).