The book ‘Reef Fishes of Saint Martin’s Island, Bangladesh: An identification book with DNA barcodes’ is the first book exclusively devoted to the coral-associated and rocky reef fishes of Bangladesh containing clear photographs with information on the habitats, distribution, key taxonomic features, DNA barcodes and global conservation status of 141 species of 55 families found in Saint Martin’s Island. Among these described species, 37 species of reef fish are recorded for the first time in Bangladesh and one is discovered as the new species to science. DNA barcodes (COI and/or 16S rRNA gene) of 103 species of reef fishes are reported in this book. In addition, a list of reef-associated fishes with valid references reported in the marine water of Bangladesh other than the present study is also provided in a summary table which includes a total of 200 species of 17 orders and 63 families. Among these, 73 species belong to 11 orders and 32 families are confirmedly recorded from Saint Martin’s Island. Considering all of the recorded fishes including the present study, the total number of reef-associated fishes of Bangladesh stands at 341 belonging to 20 orders and 79 families. The book will contribute as a reference inventory of reef fish fauna of Bangladesh and will be useful for the country’s ichthyodiversity study and future conservation plan.