Giant Kelpfish
Heterostichus rostratus

Physical Description

• Fish with a long and flattened body, shaped like a kelp blade.
• Coloring from light brown to green to purple, depending on the habitat. (In eelgrass, they can be bright green with thin silver stripes. In kelp beds, they can be brown-green like kelp). Can have wavy stripes on their sides.
• Long dorsal (back) fin, almost the entire length of body.
• Deeply forked tail fin.
• Can be up to 24 inches long.
• Juvenile fish can change colors rapidly. Adult females can change colors, but more slowly. Adult males cannot.

Range

• British Columbia to southern Baja California, Mexico.
• Uncommon north of Point Conception.

Habitat

• Live in shallow water.
• Live in rocky areas, kelp beds, eelgrass, and tide pools.
• Found near piers with heavy kelp growth.

Reproduction

• Females often lay 700 eggs at a time.
• Females deposit eggs into algal nests.
• Males vigorously guard nests for up to two weeks until eggs hatch.
• Larvae are well-developed when they hatch and stay in plankton in large schools for several weeks.

Diet

• Small fishes, crustaceans, mollusks.

Predators

• Octopuses.

Interesting Facts

• They can quickly change colors during courtship or territorial displays.
• They can also quickly change colors to camouflage in their environment.
• Larval kelpfish sometimes school with transparent mysid shrimp.

Sources: Pierfishing.com; Cabrillo Marine Aquarium; fossweb.com; Seafood Watch

Photo: Kevin Lee