Dwarf Puffer Fish

According to Wiki "The dwarf pufferfish (Carinotetraodon travancoricus), also known as the Malabar pufferfish (leading to easy confusion with the related C. imitator), pea pufferfish or pygmy pufferfish, is a small, freshwater pufferfish endemic to Kerala and southern Karnataka in Southwest India. It is threatened by overfishing for the aquarium trade, and by habitat loss.

The maximum documented size is 3.5 cm (1.4 in), making it one of the smallest pufferfish in the world. Although closely related to marine pufferfish, they are not found in salt water, and reports to the contrary are based on misidentification."