The Marbled Crayfish: A Self Cloning Wonder
Credit: The Freshwater Reef

The marbled crayfish has become a popular aquarium creature. It has a lot of personality as do many crayfish while making better community tank members than many. It is also larger than the dwarf crayfish getting to be about four inches when fully grown. While its coloring is rather boring compared to many, this doesn't deter future owners from getting excited about it. It's coloring is where its former scientific name comes from and even where many of its common names come from. This marbled crayfish isn't much to look at with a marbled blend of browns that sometimes take on a red, green, or even blue hue. It is definitely a muted coloration compared to the many bright blues, reds, oranges, and even bright whites. So, what sets this little crayfish apart and makes it an interesting pet and a potential invasive species? It's a self cloning crayfish!  

What is a Self Cloning Crayfish?

The marbled crayfish is a self cloning crayfish and is the only one of its kind. All of the specimens are females. Once they reach adulthood they will produce offspring by producing fertilized eggs inside of their bodies, releasing them and carrying them on their tail as other crayfish, and hatching them there. Each one of these tiny crayfish is an exact clone of its mother. As they get larger you can even compare the patterns and see that all the babies are the same and are smaller versions of their mother. No other crayfish has the ability to clone itself and produce more just like it.  

History of the Self Cloning Crayfish

The marbled crayfish has a mysterious history with a lot of questions and very few answers. The marbled crayfish has never been found in the wild and its actual ancestry is unknown. It showed up in the German aquarium industry some time in the 1990's. However, to this day no one knows exactly where it came from. Here is what is known though:

  •  The self cloning crayfish is a North American crayfish. North American crayfish are resistant to the crayfish plague (Aphanomyces astaci a type of water mold). This allows them to carry the mold and infect it to other crayfish especially those of the Astacus genus found in Europe. This makes the marbled crayfish even more dangerous in Europe than in North America because they can kill off the local populations very easily.
  • The marbled crayfish hasn't been found in North America. However, they seem to be related to a species found throughout Florida known as the slough crayfish or the Procambarus fallax. In fact, current scientific classification calls the marbled crayfish a Procambarus fallax subspecies virginalis. It used to be called the Procambarus marmorkreb (marmorkreb being German for marbled crab and originating in Germany.  
  • There is a lot of confusing information out there and no one is sure exactly what information can be trusted. That makes it easier to not figure out where they came from and why. They are often used in research because of their mysterious past, how easy they are to keep, and how fast they reproduce. 
Baby Self Cloning Crayfish
Credit: The Freshwater Reef

The Marbled Crayfish as an Interesting Pet

Crayfish have a lot of personality from the smallest dwarf species at around 1 and a half inches on up to the big “freshwater lobsters” that grow to about a foot in length. However, the dwarf varieties have to be kept with little fish if they are part of a community tank because fish will eat them and their babies. The larger varieties often catch and eat fish and destroy live plants. Then there is the marbled crayfish. When well fed they don't eat fish and they eat fewer plants than other varieties (at least when well fed). These characteristics make it a great option for aquarium keepers.

However, the self cloning crayfish aspect is often the reason people choose this crayfish. You only need one crayfish to have lots. Each female can produce 20 baby crayfish on up with some producing 200 or more. They can have babies every six weeks or so as long as they are kept in clean water and well fed. You can learn more about the marbled crayfish care by checking out Caring For Marbled Crayfish.  

The Marbled Crayfish as an Invasive Species

While the marbled crayfish is well-loved by many aquarium owners, it has the potential to be an invasive species. The marbled crayfish has shown up in more and more waters around the world including in German, Madagascar, and the United Kingdom. This can be a really big problem and while they haven't caused the damage that they could. Here are several things to consider when it comes to concern with the marble crayfish as an invasive species.

  • The marble crayfish is “self cloning”. The fact that a single species can produce hundreds of babies all the way to thousands of babies in a lifetime is scary. Not only do you not need to release a male and a female for an issue to occur, you don't even need two.
  • The marble crayfish can handle many conditions. They survive extremes in both heat and cold. They can handle water that isn't necessarily clean. They can adapt to different foods and they will eat anything and everything.
  • Another thing that they do or rather don't do that is dangerous to native fish, animal, and even plant species is that they don't eat their own kind. Most crayfish eat their babies in any conditions and if over crowding happens then cannibalism becomes a major factor in controlling the population. 
  • Finally, because they can carry the crayfish plague they can do serious harm for native species of crayfish in areas that the crayfish are susceptible to the mold.

Whenever a new species is introduced into a body of water and it has the potential to thrive there it can do major damage. Some think of the crayfish as a new food source and think that it won't be an issue. However, it doesn't always work that way and the fact that this crayfish can survive and eat and thrive in a variety of conditions could cause major issues in areas where it is released.  

The Marbled Crayfish
Credit: The Freshwater Reef

In more and more places the marbled crayfish is getting banned. It isn't allowed in several locations in Europe including the UK and more US states are following suit. Unfortunately some people aren't careful and many species become invasive because of that. Therefore it is important that if you do decide to keep this species that you are very careful not to introduce it into any local waters. They should never be released or set free, they should not be kept in ponds or outdoor containers that could over flow when it rains, and water changes should be done in a way that even the smallest of them can't end up outside. By being responsible and careful this species can be enjoyed and we can protect our local habitats.