The tiny shortpouch pygmy pipehorse.  (Length 2 inches.)

This one is pregnant.

(Mandarinfish Reef, Lembeh Strait, Sulawesi, Indonesia)

fish; pipefish; shortpouch pygmy pipehorse; Chordata; Osteichthyes; Syngnathiformes; Syngnathidae; Acentronura breviperula, South Pacific