Shark

Also known as the mosquito fish, least killifish or dwarf top minnow, H. formosa is the smallest known livebearing fish species, and one of the smallest overall fish species in the world. It's not often seen for sale these days, although it's quite widely available in hobbyist circles. When buying these, ensure they have been identified correctly as they're sometimes confused with the much more aggressive mosquito fish of the genus Gambusia....