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Blue Crayfish

Blue Crayfish

Blue Crayfish © Chan Pei Lynn
By: Tom Palmer

Common Name: Blue Crayfish (often mislabeled as Blue Lobster)
Latin Name: Procambarus alleni
Origin: United States
Temperature: 72-76°F
Ease Of Keeping: Easy, but....
Aggressivness: Semi-aggressive
Adult Size: 6 to 7 inches (19cm)
Minimum Tank Size: 20gal
Feeding: just about anything they can get their claws on
Spawning Method: egglayer, female carries eggs under her carapace

Comments: The Blue Crayfish is a wonderful addition to any tank, so long as one keeps an eye on it. The only requirements for them in a tank is a cave to hide in during the day, and plenty of plants to climb and hide in. Proper aeration is necessary, as is filtration. They have a reputation for being vicious killers, but as far as I've found, the trick is to just watch what you put in there with them. They are very hardy creatures, and they can survive in almost any element. I will lay out some specifics here, to help you keep your crayfish happy and healthy.


When it comes to feeding, I'd say your best bet when your crayfish is young would be to start off with some shrimp pellets, but be sure to compliment them with some algae pellets or a slice of zucchini to get some roughage for them, and because it will distract them from devouring any live plants you have in your tank (I learned THAT the hard way). All crustaceans are essentially bottom feeders, so they will really eat just about anything. Crayfish do have a fairly voracious appetite, but make sure you don't overfeed (see MOLTING, below).


Territory is VERY important to Crayfish. You really only want to put one in your tank. If your tank is over 50 Gal, you can probably get away with two, so long as they had very definite territories, each with their own cave to hide in, as spaced out as possible. But keep an eye on them, and don't be surprised if one is clawless after a while; when they fight, they don't always kill, they usually fight for dominance by ripping their opponent's claws off. On the upside, single crayfish really don't need much in the way of space, so long as they're fed. Just enough so they can roam around a big, and a plant to climb on. I'd recommend putting like two or three feeder fish in with it, such as rosie reds, just in case the Crayfish needs some fresh meat.


Which brings me to my other topic. As far as getting along with other fish, well....I've been told Crayfish will eat everything in your tank that they can get their hands on. This isn't exactly true, but it's close. I keep mine fairly well fed (I stash a pellet in his cave every other day, and he's happy), and he only kills other fish if they try to eat his food. As mentioned above, crayfish are bottom feeders, so make sure anything you put in is a middle- or top-feeder. But crayfish also love to climb plants, so middle feeders aren't completely immune. Plecos are safe around crays because they have armored plating along their back, so tough-scaled fish work well. The other thing to look out for is speed. I have a baby bala shark in my tank (inch and a half...he's so cute), and he darts around the cray WAY faster than he can catch him. Same with my black skirt tetras.

Mating And Sexing

If you choose to mate your crayfish, you need patience. To tell the difference between male and female, simply pick them up. To do this safely, catch them in your net, and then place your thumb and index finger on either side of the body right behind the claws, and pinch GENTLY. This will not hurt the crayfish (they're very well armored), and will prevent you from getting nipped. And don't worry, like most crustaceans, Crayfish can stay out of water for short periods of time as long as they remain damp.

Now, hold them upside down and look underneath their tail. Right behind their last pair of legs, males of the species will have two tiny appendages that look like miniature legs. If these are not present, then you have a female.


One thing to look out for is their molting cycle. Molting is natural and healthy for them; it means they're growing. However, if you overfeed your crayfish, and the water is TOO warm (78 to 80 degrees or so), they will molt faster, and that will shorten their lifespan. In nature, crayfish come from lakes and rivers, which tend to be cold a lot of the time.

Final Notes

If raised right, your Crayfish will most likely wind up being your favorite tank denizen. I know mine is my favorite. Though, admittedly he's a bit of a bastard to the other fish. He delights in chasing them away and claiming multiple areas of the territory as "his". In fact, before typing this, I had tossed two algae tablets on either side of the into his cave just for him, and one on the far side of the tank for the other fish. While writing this, I watched him devour most of his tablet, then race to the other side, scare the fish away, and drag their tablet away to his cave for later dining. He's funny like that.

No matter what you do, I hope you truly enjoy your Blue Crayfish. Good luck!


Name: Sarah
Comments: First of all I would like to say great job on this webpage, very well organized. I got my blue crayfish about a month ago and he is so cute. But I will addmit he can be a pain somtimes, when I brought home my angelfish and my 3 kissing gouramis within a week they had all dissapeared I finally figured it out when I cought him eating 1 of my kissing gouramis. Other than that hes one of my favorite aquarium residents that I have ever had. So I guess it just matters what you mix with them.
But he is so funny... this morning I found hanging from one of my floating plants to get the floating pellet. Image
I think these little guys make great pets.

Name: Nikki
Comments: Its a very nice webpage. I also agree that blue crayfish are very cute. However, ours has killed well over 10 fish. Mostly gouramis, so we switched him to a new tank with cichlids. However, he killed three in a matter of a day. I recommend getting a crayfish and putting him in his own tank because ours did not mix well with any other fish except sharks. They're a great addition... but don't be suprised if your population in your tank decreases.

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Comment : i'v had my red claw crayfish for awhile now and not only is it fun to watch but it keeps my tank clean!! The other day i was surprised to see it \had molted and turned blue!! is this normal?
Posted by zoeojc on 2009-05-27
Comment : I got a blue crayfish about one year ago. She (which I found out later) was not very fun she hid all the time. So about three months ago I bought another so she could have a friend. Here it turned out to be a male. They mated and had babies a couple weeks ago I removed 12 babies to a seperate tank which they are doing great. Then a couple days ago I seen them mating again! I'm having fun reading up on them and their care. Talking about funny things, I put two algie wafers in the tank and the each got one and while holding his he chased he around the tank trying to get hers I was funny. He is much bigger then her but she stands up to him all the time. I have a 55gallon which allowes them to have their space when needed.
Posted by Diane on 2008-12-11
Comment : I have had many blue crays in my big tank with plenty of tankmates, 4 angels 2 gouramis 2 yellow labs 2 plec and 2 bumble bee cats. I think as long as they are fed well they wont cannibalize or eat your fish. I now have over 60 of them the mother about a month ago. Getting really crowded.
Posted by Douglas on 2008-08-18
Comment : This is by far the BEST page on the net for information about blue lobsters. We just lost one and my husband was convinced that our cichlid's had taken him out...but I see now with the territorial issues that I think he got ripped apart by the original lobster that had been in the tank for a few months. Is there anything else we can give them for protection while molting (besides their "home" caves)?
Posted by Katie on 2008-06-26
Comment : my children and i have caught crayfish in the lake brought them home put them in a shallow water aquirium and they keep dying the next day whay are we doing wrong.
Posted by alrica evans on 2008-06-13
Comment : thanks i needed this info for a school project
Posted by Tannis on 2008-05-28
Comment : I have had my crayfish for a month and he has molted 2 times already. the last time, he lost wone of his front claws! What can I do? will it grow back?
Posted by Kris on 2008-03-31
Comment : I got my crayfish like a week ago. When i found this webpage it helped me learn how to take care of one. I only new little about the crayfish and know i know enough to take great care of it. He is fascinating and my favorite creature in the aquarium. Almost every day i watch him since i got him. What i am trying to say is thks for the info.
Posted by Leo on 2007-10-11
Comment : Wow! What a great webpage. My partner and I have 3 Blue Marron Crayfish in a 4 foot tank with a variety of African Cychlids. Each cray has its own cave situated in different places away from each other and they all get on very well with each other and the other fish. So far no casualties! I must say they certainly have real personality as they perform their accrobatics around the tank climbing, diving and flying with expertise. We have many laughs watching their antics. Today was the first time one had shed its skin and we thought for a moment that we had lost one which we were very sad about. But much to our delight they are all well and healthy. Your webpage has been very informative and has helped us to understand what is happening with our little friends. Thankyou!
Posted by Shelley on 2007-08-17
Comment : HI there, great website, i had 5 elecrtic blue marron (its waht we call them in Austraila), in my tank, heaps of hiding places, i didn't know what was going on when i fisrt got them cause they were all trying to get out, after 1 got out and died, and 2 others dies i relised that the water temp was too hot, (no heater either) its just the australian summer, so i have to buy a chiller for it, now the 2 that are left are enyoying it very much. i also found that if you drop the water level abt 3 inches from the top it makes it harder for them to escape. also i done a bit of reseach, if you have a red claw crayfish, and you have lighting on the tank, in some cases it will cause them to turn blue.
Posted by Paulie on 2007-01-26
Comment : I have two crayfish who live seemingly happily together. They live with four angel fish, four neons & a small crab who are far too fast for them to catch. One thing that I have done is to place a couple of plastic tubes into the tank which they love to hide in during the day. A floating plant is good too as you will sometimes find them taking a ride on it as the filter pushes them round the tank! I feed them prawns, chicken as well as the usual things the rest eat.
Posted by dan on 2006-11-08
Comment : I keep my crayfish in a 10 gallon and at 80 degrees is that safe,he is abot 3 months old and has molted twice. He eats veggies, tropical flakes and a gold fish at least once a day
Posted by justin on 2006-10-01
Comment : thank a lot for the info
Posted by miguel d. on 2006-09-08
Comment : I bought my blue crayfish about a week ago and put him into a 55 gallon African cichlid tank. I was worried that my fish, which range in size from 3 inches to 6 inches, would eat her. They started after her almost immediatly, but she sat back on her tail pinchers out and latched on to my large ice blue. She rode him all the way across the tank, it was kind of funny. She's missing one anntena, but both the fish and the crayfish now respect each other. She is an awesome addition.
Posted by Candace on 2006-07-15

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