Aquaculture is one of the fastest-growing sectors for food production. The development of the aquaculture industry has led to the emergence of various bacterial diseases. One of the leading causes of fish diseases is Streptococcus species. The genus streptococcus is large and complex, accommodating a wide range of gram-positive bacteria. Streptococcus iniae, streptococcus agalactia, and streptococcus dysagalactia are the most pathogenic species. Bacterial diagnosis based on phenotypic and biochemical identification methods has been routinely used. In this review,  light is spotted on worldwide distribution, diagnosis, transmission, pathogenesis, and histopathological changes. Antibiotic sensitivity and vaccination are the most effective control methods for the disease.