Plainfin Midshipman

Porichthys notatus





The plainfin midshipman is considered a deep sea marine fish.  Although referred to as a deep sea fish, the Porichthys notatus vertically migrates to the dynamic intertidal zone for breeding season within the summer.  While the plainfin midshipman can be found in a variety of locations ranging from the deep sea to the intertidal zone, the geographic distribution is along the Eastern Pacific Ocean.  The P.notatus feeds on crustaceans and smaller fishes while being preyed upon by sea lions and seals.  In respect to the reproductive system, the particular species is oviparous which means that the fish produces the young by laying eggs throughout their external environement.  One interesting fact includes that male plainfin midshipmans guard the egg grouplings until hatched.  The nests remain within small crevices under rocks in which the eggs are deposited on the tops of the cavities.  The eggs can be deposited in groups ranging from 19 to 800 eggs (1).  In regard to physical attributes, the P.notatus has a compressed body that is elongated.  The body coloration is iridescent purple and bronze.  Under the eye is a white blotch with a dark crescent below it (2).

(1) Bass, A. H. (1990). Sounds from the intertidal zone: Vocalizing fish. BioScience, 40(4), 249–258.

(2) " Species: Porichthys notatus, Plainfin midshipman." Smithsonian Tropical Research Institute, STRI,

Photograph ©2012 Douglas Klug


  • Deep sea and intertidal zone