Sharks are primarily marine; no sharks are known to be confined to fresh water. Sharks are widely distributed in all oceans, from the Arctic to subantarctic islands, and from close inshore on reefs, off beaches, and in shallow, enclosed bays to the lower continental slopes, the abyssal plains, sea mounts and ridges, and the high seas. They are most diverse in continental waters of tropical and warm-temperate seas, from inshore waters down to upper continental slopes, but are less so in colder
waters, at great depths (below 1,500 to 2,000 m), in the open ocean and off oceanic islands. World-wide there are 33 families, 101 genera, and between 379 to 478 species of sharks. Mature sharks vary in total length from about 15 to 19 cm (dwarf species of Squalidae and Proscyllii-dae) to 12.1 m or more (Whale shark, family Rhincodontidae) range in weight from between 10 to 20 grams to several metric tons.

Over the past four decades, human exploitation of sharks has seriously increased worldwide. Shark fins have become one of the world’s most lucrative fisheries commodities. This was because sharks have become a valuable resource. This paper introduces the 25 sharks species commonly found in Southeast Asia from in total of 116 species distributed in the region. The article also provides a key to order, biological parameters, habitats and ecology, and impact on fisheries.