The world’s slowest fish is the dwarf seahorse.
According to the 2009 Guinness Book of World Records, seahorses are easily the slowest fish in the ocean. This is primarily due to their small size and inflexible body structure. The majority of their potential thrust comes the tiny fin located on their back. This dorsal fin flips back and forth to create a ripple in the water that drives the tiny creature forward. Nevertheless, seahorses are typically incapable of swimming against a current, so in these situations they hold on to the coral and plant life that line the sea floor with their prehensile tails. Because smaller seahorse varieties such as the dwarf seahorse do not grow beyond a length of 1.7 inches, they inch along through the water at a maximum speed of about 0.001 miles per hour!