Haematological indices are essential diagnostic tools used to evaluate the health status of fish. Many publications have been stated by different works that qualitative and quantitative variations in haematological parameters; for instance White Blood Cells (WBCs), Red Blood Cells (RBCs), Haematocrit (Hct), Haemoglobin (Hb) content, Mean Corpuscular Haemoglobin Concentration (MCHC), Mean Corpuscular Haemoglobin (MCH) and Mean Corpuscular Volume (MCV) in fish, offer an indication of the health status of the fish. The uses of probiotics as biological control agents in aquaculture have replaced the usage of chemotherapeutics, is an approach in the build-up in aquaculture environments. In the cultured fish, the use of probiotics in monospecies or multispecies forms has been reported to stimulate specific and non-specific immune parameters including lysozyme activities and phagocytic, expression of various cytokines as well as improvement of blood profiles of many fish increasing resistance diseases and to other environmental perturbations such as physiological stressors. Interestingly, many researchers have shown that haematological indices in fish continue to offer a valuable diagnostic tool; and progress is made in establishing a reasonable range of values for blood parameters of different fish species. Also, many interventions have shown that probiotics used in aquaculture have potential in improving blood profiles of fish; although there are not many summarised information regarding the effects of probiotics on haematological parameters in fish. The purpose of this review is to synthesise the influences of probiotics on haematological parameters in fisha.