The present study examined the health status of marron Cherax cainii after feeding with a customised probiotic B. Mycoides supplemented diets at various feeding period by measuring intestinal bacterial population, hepatosomatic indices (Hiw), total haemocyte count (THC), bacteraemia and survival rate. During a 6 week feeding trial, the marron were fed at a rate of 1.5 % of the total biomass per day with a commercial marron feed (basal diet) and B. mycoides (10 8 CFU/g of feed) supplemented diet. The first group of marron was solely fed on the basal diet while group two, three and four were fed with supplemented probiotic for one week, two weeks and four weeks, respectively before changing to the basal diet only.The results suggested that intestinal bacterial population was higher in the probiotic fed groups compared to the basal diet fed marron. Among the probiotic fed groups, the highest intestinal bacterial population was observed in marron fed probiotic for four weeks. In addition, Hiw of the marron fed probiotic for four weeks was also higher than other feeding groups, whereas Hiw of basal diet fed marron was significantly lower compared to probiotic fed groups. No mortality was observed in any feeding group.The longest probiotic feeding period (four weeks) resulted in a higher immune status as indicated by higher THC and lower bacteraemia. However, after shifting to a basal diet, a reduced intestinal bacterial population, Hiw and THC were observed in all groups, except bacteraemia. In conclusion, periodic or continues probiotic B. Mycoides feeding is required to maintain its high population levels and better health benefits in marron.