Smallest Fish in the World
If you want to know the record holder for the smallest fish in the world, then you're in the right place. The world's smallest fish is Paedocypris progenetica, it's also the smallest vertebrate or backboned animal. Scientists have discovered this fish living in forest swamps on the Indonesian island of Sumatra. It only measures 7.9mm long (0.31 inch). Male individuals of the species anglerfish Photocorynus spiniceps have been documented to be 6.2-7.3 mm at maturity, and thus claimed to be a smaller species. However, these survive only by sexual parasitism, and the female individuals reach the significantly larger size of 50.5 mm.
It's important to mention that the dwarf pygmy goby (Pandaka pygmaea) is also one of the smallest fish in the world by mass and is also one of the shortest freshwater fish as well. Mature males can reach up to 1.1 cm, while the females can grow up to 1.5 cm. Average weight is from 4 to 5 mg. It is a tropical freshwater fish of the family Gobiidae. It is known as bia and tabios in the Philippines.