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What color are crawfish in California?

Crawfish, also known as crayfish or crawdads, come in a variety of colors in California. The most common crawfish species found in California are the Signal crayfish and the Red swamp crawfish. The color of crawfish is influenced by their habitat and diet.

Quick Answer

The most common colors for crawfish in California are red, brown, and green. The typical color is a dark reddish-brown. However, some crawfish can also have a greenish color, especially in areas with abundant aquatic vegetation.


There are over 500 species of crawfish in the world, with the majority living in North America. Two species are most prevalent in California – the Signal crayfish and the Red swamp crawfish.

The Signal crayfish (Pacifastacus leniusculus) is a large crayfish native to the Pacific Northwest but introduced to California in the early 1900s. They are commonly found in northern and central California.

The Red swamp crawfish (Procambarus clarkii) is native to the south-central United States and northeastern Mexico. It has also been widely introduced outside its native range, including throughout California.

Both species thrive in the warm waters of California. They can be found in lakes, rivers, streams, irrigation ditches, rice fields, and ponds statewide.

Typical Crawfish Colors in California

The most common color of crawfish in California is a dark reddish-brown. This is the natural color of both Signal and Red swamp crawfish. The reddish hue comes from the pigment astaxanthin, which helps protect the crawfish against ultraviolet light.

When the exoskeleton is still soft after molting, the crawfish color may appear more orange. After the new exoskeleton hardens, it darkens to the reddish-brown shade.

Here are some of the typical colors seen:

  • Dark reddish-brown
  • Reddish-orange
  • Dark orange-brown
  • Olive green to brownish-green

The darker brown and red hues provide camouflage for the crawfish against the muddy or vegetated bottoms of their habitats. The color can help conceal them from predators.

Factors Influencing Color

Several factors can influence the specific coloration of crawfish in California:

  • Species: Signal crayfish tend to be dark reddish-brown. Red swamp crawfish may show more orange/red hues.
  • Age: Young crawfish tend to be lighter in color. Older crawfish are usually darker.
  • Molting: After molting, the new exoskeleton has brighter, lighter colors until it hardens and darkens.
  • Water temperature: Cooler water can make the colors darker.
  • Diet: Food sources like aquatic plants can impart some greenish tones.
  • Habitat: Muddy bottoms lead to darker browns. Vegetated areas contribute to greenish hues.
  • Sun exposure: More sun exposure causes darker coloring.
  • Stress levels: Stressed crawfish may appear lighter or pale.

The interaction of these factors results in the range of colors seen in California crawfish. The species, age, diet, habitat, and sun exposure have the biggest impact on overall color.

Greenish Crawfish

While reddish-brown is the most common, some crawfish in California can display olive to greenish coloration. This is especially true in areas with an abundance of aquatic plants.

Crawfish will naturally blend in with their surroundings. Living among green aquatic vegetation can result in greener tones in their exoskeleton. A diet high in plant matter may also impart more green hues.

Algae growth on a crawfish exoskeleton can also contribute to a temporary greenish tint. However, the algae will be shed during the next molt.

Greenish crawfish are more prevalent in rice fields, agricultural ditches, ponds, and lakes with lots of vegetation. The environment provides camouflage and food sources that influence color.

Unusual Colors from Mutations

On very rare occasions, unusual colors of crawfish may be seen in California:

  • Blue crawfish – A genetic mutation resulting in a blue pigment.
  • White crawfish – Lack the usual orange/red pigments.
  • Purple crawfish – A combination of blue and red pigments.

These unique color variants originate from captive breeding programs. They are not found naturally in the wild in California. Only the typical reddish-brown, green, and orange crawfish occur naturally.

Differences Between Males and Females

There are some subtle color differences between male and female crawfish:

  • Males tend to have brighter red claws with white/grey tubercles at the joints.
  • Females usually have slightly duller claws and smaller tubercles.
  • Males have broader tail fins with a notch in the center.
  • Females have narrower, rounded tails to hold eggs.

However, these differences are difficult to discern on sight alone. The most reliable method for determining sex is to examine the underside. Males have larger hook-shaped reproductive organs compared to small round openings on females.

Crawfish Color Based on Location

Here is an overview of the typical crawfish colors found in various parts of California:

Location Typical Color
Central Valley Dark reddish-brown
Sierra Nevada Foothills Reddish-orange to brown
Rice Fields Greenish-brown to olive green
Agricultural Canals Dark brown to greenish
Tule Marsh Wetlands Dark brown to blackish
Coastal Wetlands Greenish-brown

As shown, crawfish from vegetated wetlands and agricultural areas tend to display more greenish hues. Crawfish from open waters and muddy substrates are generally darker brown and reddish.

Summary of Crawfish Colors in California

In summary, here are the key points on crawfish colors in California:

  • The most common colors are dark reddish-brown, reddish-orange, and brown.
  • Greenish hues may be seen in crawfish living among aquatic plants.
  • Young crawfish tend to be lighter in color.
  • Factors like diet, habitat, and sun exposure influence color.
  • Unusual colors like purple, white, and blue are extremely rare.
  • Females and males show subtle color differences in their claws and tails.
  • Location also impacts colors based on habitat.

So while dark brownish-red is the most prevalent, crawfish in California can display a range of hues from orange to green depending on their specific environment. The diverse aquatic habitats across the state lead to interesting regional color variations.

Frequently Asked Questions

Why are some crawfish bright red?

The bright red color seen in some crawfish is usually due to their young age and recent molting. Young juvenile crawfish and those who have recently molted will temporarily display more vibrant orange-red tones before their exoskeleton hardens and darkens to the typical reddish-brown shade.

What color are wild crawfish?

Wild crawfish are almost always some shade of brown, reddish-brown, or greenish-brown that helps provide camouflage in their natural habitat. Bright red or other unusual colors are primarily seen in captive-bred varieties.

Do crawfish change color as they grow?

Yes, young juvenile crawfish usually have brighter reddish-orange claws. As they mature, their coloration becomes darker and more brownish-red. Older crawfish also take on more green if living among aquatic plants.

Why are crawfish green sometimes?

A greenish color in crawfish is primarily caused by their habitat. Living among green aquatic vegetation can impart some green tones. Algae growth can also lead to temporary greenish tints. Their diet of plants may further contribute to green coloration.


Crawfish in California display a beautiful array of colors. While dark red and brown hues are the most common, the diverse aquatic habitats support interesting variations ranging from bright orange to olive green. Factors like age, diet, surroundings, and genetics all play a role in determining the specific coloring.

So next time you see a crawfish, take a moment to appreciate its vivid colors. The unique color patterns of California crawfish provide camouflage and are suited perfectly to their environment!