I have a Marbled crayfish

I thought that's what it was when I saw it in a petshop and when I bought it was partly out of curiosity and also because if I was right then I didn't want someone who didn't know what it was to buy it. Marbled crayfish also known as Marmokrebs have a unique ability. They are the only crayfish species ables to reproduce by themselves. All Marbled crayfish are females and they self fertilize their eggs and lay exact clones of themselves. I got a good look at her last night for the first time in a couple of weeks and she's pregnant with fertile eggs.

Now I have to figure out what to do with her. Her babies will go into my 75 gallon tank as a food source for my bluegill, shiners, possibly my loaches and for the other crayfish. Hopefully they will get them all. I really don't want to keep her but I'm not the type to kill something I bought or caught just because I've decided I don't want it anymore. I could still possibly be wrong since female crays can carry a males sperm for up to 6 months but I'm about 99% sure she's a Marble. I guess as along as I don't get overrun by them I'll be okay.

If you don't want it I'd be delited to take it off your hands! However, they are a great food source, so if I were you I'd be delited to find one, but they can get overwhelming.

I might have to take you up on that offer Yeahson421, I currently only have one sunfish in my big tank but I do have an Eastern Mudminnow in the same tank as the Marbled crayfish so hopefully it will eat some too. If I get overwhelmed I'll be more then happy to send some to you though.

I recently bought some myself off Aquabid. They're popping up for sale all over the place. At least one of mine is berried. I originally bought them for freshwater puffers but won't be getting puffers and don't really know what to do with the off spring. :/

This sounds like a reliable, easy to care for live food source, but before I get too excited I should ask a few questions. First, how often (on average) do these crayfish produce broods? Second, approximately how many baby crayfish hatch out of each brood? Finally, what size are the baby crayfish upon hatching (i.e. what size range of fishes are capable of eating them)?

The reason I am interested is because it can be expensive to buy live foods for medium to large fish, and raising some of them to a size big enough to fill up a large fish can be tricky and/or smelly and/or time consuming and/or not very high in carotenes (see earthworm cultures, egglaying feeder fish, feeder guppies, ghost shrimps, etc.).

When I get to college and can set up 29- and 55- gallon aquariums that were kindly given to me, I really would like to collect a few more Orangespotted Sunfish and try my hand at breeding them. However, the single male that I have right now does not like the taste of flakes and ignores cichlid pellets completely... but he vivaciously tore apart a crayfish that was in his aquarium and devoured it happily. Obviously, once I'm a college kid, I won't have the kind of money needed to buy him frozen bloodworms (they don't fill him up very fast) and ghost shrimp every month, and since I plan to have more than one it will be even more mouths to feed. These marbled crayfish sound like they could be a good solution...

Orangespotted: Buy a bag of frozen uncooked shrimp (small size). Your fish will love them in small bits and the $5.00 bag will last you months.

Usil

These things are terrifying. Like any crayfish they can climb, so you need a very tight tank to prevent escapes. I took apart a 30 gallon tank to move last year. I thought it contained 6 crayfish. I found 27 by the time I had all the rock out. Then I found half a dozen more after I bleached it to be sure.

They can have eggs up to every 2-3 weeks, depending how well fed they are and how overpopulated the tank already is. I haven't counted a brood very systematically. It's dozens at least. They are very small, suitable for anything much bigger than Elassoma. However, they grow fast and are quite adept at hiding. Even in a tank that had multiple large sunfish and a bass I found 20+ crayfish that had survived being added from the surface as feeders. These showed evidence (in their size) of having survived in the tank for quite some time.

If you must keep them, please be very careful - don't flush water change water down the toilet or set up a tank in any way that could allow escape. Last time I did a water change on a tank containing them I saw two get scooped up, but then I looked through the muck collected in the bucket and found 34 little ones...

I heartily second the suggestion of frozen shrimp.

Edited by gzeiger, 07 July 2012 - 10:59 PM.

Unless some are still hiding out somewhere mine are all gone. I had found some babies while cleaning out one of my canister filters a while back but I have 2 Tadpole Madtoms and one Juvenile Bullhead and even when I did a major tank cleaning/re decorating I didn't find any, The only downside is that the Bullhead is big enough to be eating some of my other crayfish and some have gone missing. He's going into a friends pond but not until spring. I will not be putting any new crayfish in my 75 gallon until he's gone.

I wonder if you keep them in a separate tank and just raise them as live food for the babies to feed to your fish?

Usil

I do that. I keep them in a 50 gallon sump and occasionally net them to drop into the 75 gallon tank above. I can't recommend it in a warmer climate where they could survive outside though.