Trimmatom nanus is a species of dwarf goby native to the Chagos Archipelago and the Maldives in the western Indian Ocean.
With adults growing to a total overall length of just over 10 mm (less than one-half inch), T. nanus was until 2004 the shortest known fish and vertebrate. The recent discovery of Schindleria brevipinguis (called the stout infantfish) relegated it to second place. After discovery of Paedocypris progenetica, Trimmatom nanus is on third place.
Image © Rick Winterbottom