The Lesser pipefish or Nilsson's pipefish, Syngnathus rostellatus, is a pipefish similar to the greater pipefish, but with no crest above the head. Usually it reaches up to 17 centimetres (6.7 in) in length, maximally 18 centimetres (7.1 in), although in South Wales they are usually not more than 10 to 13 centimetres (3.9 to 5.1 in) long. They have a light to dark green-brown colour with bar-like markings on the sides (compare the greater pipefish).