Paedocypris progenetica was once considered the smallest fish in the world, measuring around 7.9 millimeters. However, that title is now disputed. Recent discoveries have revealed similarly tiny species, including the dwarf goby and the stout infantfish, both measuring roughly 7 millimeters. Because new species continue to be found, scientists have not declared a single definitive smallest fish.
The search for the tiniest fish remains an active area of research.