Tatsugiri is a small piscine dragon Pokémon that comes in three forms. All forms share the same basic physiology, with two large eyes, long pectoral fins, a wavy dorsal fin, and a split tail fin.

All forms also have a white throat sac, which resembles a bed of rice when inflated; Tatsugiri inflates its throat sac to camouflage itself. The major difference between each form of Tatsugiri is its colors and the poses it makes. Curly Form Tatsugiri is orange with darker orange splotches all over its body and a white underbelly, and it often assumes an upcurled stance.

Droopy Form Tatsugiri is mostly a pinkish-red, with white colorations on its belly and fins; true to its name, it tends to droop on its throat sac. Stretchy Form Tatsugiri is a solid yellow, except for its white throat sac; it assumes a straight, horizontal pose. It is said that Tatsugiri's various forms are an adaptation to suit the preferences of its prey.