Procambarus clarkii

Family Cambariidae

Origin: the swamps of Louisiana, United States of America

Recent Distribution: All Europe

Comercial Name: Red crayfish / Louisiana Crayfish

Size: up to 20 cm

Adequate Environment: can cope with all types of water, nevertheless it has a preference for hard water.

Temperature: 15 to 28░C

Feeding:  Omnivorous, with a preference for vegetal based diets

Utility: Very pretty

Particularity:  very aggressive, even with its own species.  Territorial and soft or thick leaved plant eater

 

Menacing attitude, watch your fingers.

Nice specimen isn't it ?

I spent some holidays in Lisbon, Portugal.  I noticed a pond in what - to my surprise - dwelled crayfishes.  I couldn't resist and I caugt some.  Back home, I placed them in a "specific" aquarium (meaning with no fishes).  I had seen them capture and cut to pieces some regular sized tilapias captured in the pond so I had decided that wouldn't happen to my fishes.  But I left some snails in the aquarium, just to see what would happen ...

It seems that my interpretation on the tilapia's massacre was wrong, the fishes died due to lack of spacing during transport and the crayfishes did eat the dead ones ... sorry for this poor image I transmitted of you Dame clarkii.

Right after it was captured, see how this banjo-fish was killed and skinned !  All the skin from the head has been pulled down to the tail. Whereas the snail apparently represents no major interest for the crayfish, the banjo-fish will quickly be cleared of all his meat. After three hours, a nice and clean squeleton ...

I want to stress the following:  the fish depicted hereabove was almost dead when it was captured by the crayfishes, it was irremediably condemned due to disease and what happened is a "natural cleaning" performed by the crayfishes.  They are quite unable of grabbing a sound fish.

Despite being fond of all types of meat, crayfishes do not harm ampullariidae or sound fishes; nevertheless they clean and eat every dead body in the aquarium, what might prove quite useful for hobbyists who have some difficulty in spotting dead snails - the latter being a major source of pollution.  After the crayfish consumes the flesh, there remains a nice clean shell, useful for the breeding of shell dwelling fishes or as decoration, on top of a shelf with the rest of the shell collection.  

Another important element concerns the moult of crayfish:  their shell is constituted of chitin (like the carapace of insects). As Ampullariidae - even in the best maintenance conditions - don't find all the elements required to their development, they eat the moult.  Therefore chotin is bound to be a component of one of their "organs".  It is possible that it is necessary to synthesize conchiolin (hormone specific to gastropods, composing the operculum). It seems that after all, the association "Ampullariidae / crayfish"  (or shrimps) is an excellent one!   Furthermore, the moult is filled with calcary, an essential element for the development of the snails shell.

Until I manage a better identification, I consider these crayfishes to be Procambarus clarkii species, Familly Cambaridae, the Louisiana crayfish.

Dame crayfish protectin her eggs. Zoom of the clutch. The eggs are one day old ! Closer look at the eggs.
The larvae were born after 21 days of incubation ! This one is 5mm long and 2 days. A miniature crayfish with all the attributes of adult ones. 1 month later, 2 cm. Juveniles frequently moult.  here you can see the scission between the cephalothorax and the abdomen, just the moult actually occurs.

This crayfish is forbidden in France and is being commercialized in a very particular way.

So as to avoid this law, producers feed it algae and keep them in aquaria with no lighting.   After a moult, its color is vivid red, and its species name changes to become Procambarus sp. "China Red".   the hobbyist will pay hard cash for this "new species", feed it as is required and after one moult the crayfish color turns back to the original.

Summary