This study presents a comprehensive review of probiotics usage in aquaculture with a specific emphasis on our research series on the effectiveness of the customised probiotics, Pseudomonas synxantha and Pseudomonas aeruginosa on the cultivation of western king prawns, Penaeus latisulcatus. These customised probiotics resulted from tests using five inhibition test methods between the bacteria isolated from two commercial probiotic products and Vibrio spp. isolated from western king prawns and other aquatic animals. The results proved the suitability and safety of these probiotics in the cultivation of western king prawns as they conclusively met all the essential requirements for appropriate probiotics. These probiotics have shown similar beneficial effects as the common prebiotics, Bio-Mos and beta-1,3-d-glucan on the growth, survival and immune responses of the prawns. The supplementation of probiotics with the formulated feed was more efficacious and more practical than direct application into the rearing media. The prawns exposed to the combined probiotics were healthier than those exposed to the individual probiotics. P. aeruginosa was more effective for improving prawn health than P. synxantha. The probiotic-fed prawns were not influenced by Vibrio harveyi at 10(3) CFU ml(-1) for 36 h of challenge. In conclusion, these customised probiotics can be used as appropriate probiotics and as a suitable replacement of antibiotics, for disease control in western king prawn aquaculture.