specifically, 18 species live in Australia, 6 in New Guinea, and 1 in East Timor. How Craterocephalus diverged from being marine water organisms is linked to the ancestors of Craterocephalinae and Atherininae, where both subfamilies lived in similar environments but were separated by a North-South disjunction around Australia. The separation caused one lineage to remain in Northern Australia, forming the genus Craterocephalus, which developed distinct characteristics from the other subfamily Atherininae. Since all of Atherinidae are primarily marine, Craterocephalus is most likely also of marine origin. Freshwater fish in the genus Craterocephalus are found in various ecosystems, such as rivers, rainforest streams, creeks, and hot desert springs. Characteristics of the fish include having short life spans that are 2–3 years long, and their body length ranges from 5–10 cm. Maturity is reached when fish are 3–5 cm in length, and most species spawn shortly after one year of being born. Spawning rates increase in the spring and continue to be high in the summer — typically, one fish releases 85 eggs daily. Species in this genus are tolerant of environments differing in salt concentrations and temperature, especially C. eyresii and C. cuneiceps. Both these species can tolerate 70-100 ppm of salt, while C. dalhousiensis can withstand high water temperatures up to 42 ℃. The genus is split into five groups: “eyresii”, “stercusmuscarum”, “new honoriae”, “capreoli”, and “stramineus”. Two groups, “eyresii” and “stercusmuscarum”, are mainly found in Australian freshwaters. The majority of the fish in the “new honoriae” are marine organisms found in the Northern area of Australia, and their habitat slightly overlaps with the habitat of fish in the subfamily Atherininae. After the formation of the Craterocephalus, the “new honoriae” group established itself in Northern Australia’s marine environments, while the other groups invaded freshwater habitats. Species within Craterocephalus Craterocephalus stercusmuscarum is an Australian freshwater fish of marine origin that has moderate dispersal potential. The species is abundant in the Wet Tropics of Northern Australia and travels long distances upland to areas near waterfalls. Subfamily Atherininae Origin of Atherininae The separation between the ancestors of Craterocephalinae and Atherininae caused Atherininae lineage to form in Southern Australia, which has cooler habitats than Northern Australia. The subfamily Atherininae has five genera. One is Atherina, which is found near the Eastern Atlantic and Mediterranean oceans; however, the remaining four are restricted to Australia’s southern coastal waters. Since Atherina’s biogeographic location is significantly different, it