Outdoor Corner: Crawfish biology

Lyle Johnson

Most discoveries, even the very important ones, are sometimes the result of a mistake of sorts. A scientist looking for something might well discover something great instead of what they were looking for.

Maybe it’s an inventor trying to come up with some revolutionary idea only to invent something else. Take Post-It Notes (Sticky Notes as we know it today) for example. In 1968, Spencer Silver was working at 3M trying to create super strong adhesives for use in the aerospace industry in building planes. 

This is what they look like; a beautiful, blue crawfish.

Instead of a super strong adhesive, though, he accidentally managed to create an incredibly weak, pressure sensitive adhesive agent called Acrylate Copolymer Microspheres. It did have two interesting features, though. 

The first is that, when stuck to a surface, it can be peeled away without leaving any residue. Specifically, the acrylic spheres only stick well to surfaces where they are tangent to the surface, thus allowing weak enough adhesion to be able to be peeled easily. 

But after five years of constant rejection for the adhesive and another seven years in development and initial rejection, Post-It notes were finally a hit and have since become a mainstay in offices the world over. Today they are one of the top five best-selling office supply products in the world.

So it was with my biological education about the highly regarded crawfish. My first inspiration was to get an aquarium. I purchased a 33-gallon model to get started. I knew I didn’t want saltwater species because that was way too much trouble and upkeep.

So freshwater it was. There was no interest in store bought, multi-colored fish. I was looking for what swam in our local rivers and bayous. After setting up the aquarium with rocks on the bottom, all sorts of castles and stuff to swim through and some plastic grass to hide in, the quest to fill it with local fish began.

Kaze Breaux caught this nice redfish fishing four miles out of Grand Isle at a reef site targeting mangrove snapper using cut mullet on snapper rigs.

Slowly but surely the aquarium began to take shape. Small bluegill and sunfish were pretty easy to come by. Then a baby sac-a-lait, goggle-eye and catfish rounded out the collection.

One day I was throwing my cast net to catch some bait for our trot lines at our family camp on Chinquapin canal. I caught what turned out to be a spotted sucker. It was 6 inches long with the mouth on the bottom of its head; very unusual. But I knew where it was going. Straight to the fish tank.

This would turn out to be a very fortunate occurrence as the fish would swim around the tank sucking the small rocks into its mouth and appearing to suck the algae and any trash that was attached to it. The fish would then eat what ever was on the outside of the rocks, then spit it back into the water. It was a pretty good aquarium cleaner.

DeShae Gautreaux caught this beautiful redfish fishing with her husband, Spencer, off Grand Isle.

As I was admiring the setup one day, I thought to myself, “Man, I’m missing something; crawfish!” So out to the ditch with the dip net it was to give it a try. I caught two small crawfish about 3 inches long and added them to the collection. “Now it’s complete,” I said.

After returning from church one Sunday, I took a look at my pride and joy to notice the two crawfish in that plastic grass, belly to belly. My first thought was, “Are they mating?” Then I thought, “What are the odds that I would catch two crawfish and one would be male and the other female?”

Sure enough a few weeks later there was a ball of baby crawfish under her tail. They were clear to see through and appeared to be just a head and no tail. It took about a week for them to completely form into a fully developed specimen. Unfortunately when they ventured out from under her tail, the fish had an easy meal.

That wasn’t the last of my education with crawfish. I set up another aquarium in my office at work and started again. I got a big male (pretty easy to tell them apart) that added to the fish. He was big enough to eat the small fish but the trick was to catch them.

So I got to watch the games at play. The male would stand up on it’s eight legs, making a tunnel of sorts. Fish can’t resist swimming through something like that so as they passed through the crawfish would try to catch them, usually to no avail as they were too fast. Every now and then he would be successful and man can they eat, sort of like a meat grinder.

Part three of my education came when I decided to conduct an experiment. There are some rare, blue (that’s right, blue) crawfish and they are beautiful. I often wondered if they were a different specie or just a gene mutation.

Since they would mate in an aquarium I decided to give it a try and put the word out that I was looking for a male and female blue crawfish. It took a while but it finally happened. The pair didn’t let me down and began the birthing process soon and often.

In 6 weeks that mom had a very large ball of babies under her tail. After they were fully formed I put some fish food flakes in the tank and she flicked her tail and out flew what I estimated to be around 700 baby crawfish. After eating for a while, she walked around the tank twice and all those babies were back under her tail.

The problem with keeping crawfish of that number in a tank is their feeding habits. They eat often and a lot so cannibalism is a huge problem. Only one crawfish survived to grow 4 inches in length and started to turn blue just before it died. That part was an incomplete experiment but I learned a lot and it was fun to watch.

So until next time, remember to keep the slack out and set the hook hard. Have fun in the outdoors, be safe and may God truly bless you!