Giant Kelpfish

Heterostichus rostratus





The giant kelpfish is a sight between Point Conception and Baja California (3). These elongated fish can be up to 11 cm long with larger females than males (1)(2). As their name suggest giant kelpfish generally live among algae along the coast (1)(2). Giant kelpfish can be red, brown or green, however they actively change their color to match their backgrounds (2)(3). Males have a harder time changing colors and can only switch between brown and olive-green, leading to the theory that color change ability is related to a sex hormone (3). They can spawn year-round, though the peak season is in the spring (2). Females lay eggs in algal nest and males guard these nest until they hatch (2).


(1) Eschmeyer, W. N., & Herald, E. S. (1983). A field guide to Pacific Coast fishes: North America. Boston: Houghton Mifflin.

(2) Stepien, C. A. (1986). ASPECTS OF THE LIFE HISTORY AND LARVAL DEVELOPMENT OF THE GIANT KELPFISH, HETEROSTICHUS ROSTRATUS (Vol. 83(4), pp. 1-12) (United States, National Oceanic and Atmospheric Administration, National Marine Fishery Service). Fishery Bulletin.

(3) Stepien, C. A. (1986). Regulation of color morphic patterns in the giant kelpfish, Heterostichus rostratus Girard: Genetic versus environmental factors. Journal of Experimental Marine Biology and Ecology, 100(1-3), 181-208.