The title for the smallest fish is often contested among various species, as there are several contenders for this title. One of the smallest known fish is the Paedocypris progenetica, a species of cyprinid fish found in peat swamp forests in Southeast Asia. Adult females of this species typically measure around 0.3 inches (7.9 millimeters) in length.
Another contender for the smallest fish is the Trimmatom nanus, a species of goby found in the Indian and Pacific Oceans. It has an average length of about 0.33 inches (8.4 millimeters).
The smallest vertebrate, including fish, is the dwarf goby (Pandaka pygmaea). It is found in the Philippines and has an average length of around 0.3 inches (7.7 millimeters).
These are just a few examples of tiny fish species, but there are other small fish species that could also be considered for the title of the smallest fish. The actual smallest fish species can vary depending on different criteria such as size, length, or weight.