Patriotic Crawfish Colors – Red, White and Blue?

blue crawfish


By Patrick D. Bonin

Crawfish boils have long been a part of Memorial Day Weekend celebrations in south Louisiana. Before we know it, Memorial Day will be here: school days will be done, vacation time will be near and the official kickoff of summer is a great time to gather together with family and friends in honor of those who have fought and died for our freedom.

Red, white and blue is the theme of the weekend, and sometimes even the crawfish themselves show their patriotic spirit! So gear up and get ready, it’s coming-fast.

Everyone is familiar with the Red Swamp crawfish typically harvested here in south Louisiana, but you might not know that a genetic mudbug mutation can also create beautiful blue specimens, and even more rare, solid white crawfish!

According to the Louisiana State University Ag Center, color expression in crawfish is regulated largely by pigment containing cells located beneath the exoskeleton. Color is normally a function of two factors: developmental stage and the environment.

“Crawfish have three different pigments in their shells that are oxidized to varying degrees: brilliant red like in the spots on the claws, black that you see down the back and the tail, and the nice rosy pink color you see on the legs,” explained Dr. Greg Lutz, aquaculture professor with the LSU Ag Center.  “Any or all of them can have a mutation that keeps them from being oxidized so they turn into a blue color instead.”

The blue and white color variations are the result of an inherited, recessive trait resulting from a mutation in the gene responsible for pigment formation. In normally colored crawfish, a carotenoid pigment combines with a protein to form the characteristic red coloration. But if that pigment-protein complex is not formed properly, then the blue color variation usually occurs. And if that complex is lacking, then the albino-like white condition occurs, he said.

“The white crawfish have a genetic mutation early in the whole process of making pigments, so they don’t make any. That’s why they’re completely white,” Lutz said. “No pigment at all.”

Lutz estimates that a blue crawfish is a 1 in 50,000 find, while a true albino crawfish is about 100 times more rare, occurring only once in 5,000,000 times!

Mark Frugé, co-owner of Frugé Aquafarms in Branch, La., confirmed that he sees several blue crawfish during a typical season.

“Running all the crawfish through the grader, we see the blue ones,” Frugé said. “I wouldn’t say it’s common, but we definitely see them because we harvest so many crawfish during a typical season.”

In addition to blue and white mutations, Lutz pointed out that other colors are possible as well. Lemon yellow crawfish have been captured, as have “bright red” ones that are “over-oxidized” and appear as if they’ve already been boiled when they’re actually quite alive and healthy. Very, very rarely, a half-blue, half-red crawfish turns up, and appears to have been painted symmetrically with blue and red paint.

Red, white and blue crawfish

Yes, these are the true colors of these red swamp crawfish. The blue is rare. The pure white is even more rare.

Lutz called those “once in a lifetime” finds, but the good news for all of us is that no matter what color they are, they all taste the same: awesome!

“Blue crawfish actually turn bright red when they’re boiled because the heat oxidizes their pigments,” Lutz said. “They’re all absolutely fine to eat!”


Photo and miscellaneous information from LSU Ag Center
Photo taken by John Sonnier in Crowley in 2004