The Puffer Forum

Hi,
I’ve run into a problem with my crayfish. I’ve had this cobalt blue lobster for quite some time, and decided today to purchase a red swamp crayfish. I knew that they could potentially fight, but they are being kept in a 60g tank with plenty of caves, rocks, and hiding spots.
However, when the new (and much smaller) crayfish began to explore, he found the blue one. And a few seconds later he was on top.
Afraid, I broke up the “fight” with a net, but over the span of an hour, they fought three more times. However, it always begins where the new one raises its claws and the blue one easily goes down. It feels like the blue one should be more powerful, but so easily winds up underneath. I’m almost certain it has to be a fight over territory, but I cannot tell.
Any advice? I really don’t want either of them to die, but especially not the blue one!! Additionally, if it is a fight, and I have no current way to separate them, who would win? Do they usually fight to death or dominance?

Sounds like they are trying to breed. Do you know the sex of each one?
The red one will eventually grow larger than the blue one, so you may have difficulties keeping them together. They are most vulnerable right after molting.

I’m not 100% sure, but it looks like the swamp crayfish is male and the cobalt is female. Just for safety I ended up moving the swamp crayfish into my SA/CA Cichlid tank (to avoid a dead crayfish or a hundred babies). They haven’t eaten him yet, hopefully they won’t (they’re all still juveniles).

What crayfish species are we talking about here?
Mixing crayfish species is never a good idea imo, different species often have a different temperament...

Procambarus clarkii also has blue color morphs so they could be the same species.
If the blue one is a procambarus alleni, then according to some people hybrids are possible.
But I’ve never seen an actual hybrid even though I helped run a shrimp and crayfish forum for years so I would consider it very rare if not practically impossible.

Mating crayfish go belly to belly, much like this picture of some dwarf crayfish i had:

So if you saw that then yes they were mating or attempting to mate. Many species can hold on to sperm, if they did mate successfully the seperation could already be to late.

Sexing is really easy with procambarus, these are pictures of a cambarus species i owned years ago. But it’s similar enough
female:

male:

is there a difference?

eieio wrote: ↑Sun Feb 23, 2020 10:37 pm is there a difference?

Difference in what? The pictures of the male vs female?
The male has these little tubular things, in the picture they have a brown discolouration because the crayfish needed to moult.

The female doesn't have those tubular shaped things (gonopods) , she has these two little dots on the base of the 3rd pair of legs.

Thanks for the helpful information! I think based on the pictures that they were trying to mate, and although I assumed this, I didn’t want to risk anything at the time. Though I’m keeping them separate, at least I know I can put them back together at some point, in the event that the cichlids try to kill it. After examining them, I definitely think that there is a difference between the cobalt blue and swamp crayfish’s undersides. As far as the species go I can only determine based on what they were sold as, “cobalt blue” and “red swamp crayfish feeder”. I do know, based on pictures I’ve seen, that that’s probably what they are. If you want I can try to post some pictures.

Mayby I wasn't entirely clear, I wouldn't advise to put 2 crayfish of different species together.
Presumably one of the reasons hybrids are so rare, is the fact that one often kills the other before they can reproduce.

I would think the 'red swamp crayfish' is probably procambarus clarkii. The cobalt blue I'm not certain, could be P. Alleni or maybe a cherax species.

If you take some pictures I might be able to make an educated guess, but I can't make any promises.

Oh, sorry about the confusion. I only really know the basics for crayfish, so you’d probably be able to tell better. I couldn’t quite get a picture of their undersides but I hope these help in their identification. The image quality for the first isn’t the best, but in person it’s a brighter brown with orange undersides of its claws.

I’m confident that the second picture is Procambarus alleni. Based upon the claws I’d guess a female, but I’m not 100% certain.

The first picture I’m not certain about, It’s a bit too small to really be able to see any details. Red swamp crayfish is generally used for procambarus clarkii. However the animals I’ve seen here in Europe where never this brownish, but red, white or blue.
Off course you’re in the states so this could be due to the fact that this is a more ‘wild’ colour and the strains here in Europe where bred for their colour.

An other option could be Procambarus fallax or procambarus fallax f. virginalis. The last one reproduces by parthenogenesis, so one animal can basically ‘clone’ itself. (and a highly invasive species as it mutated in the aquarium hobby and isn't a natural species)

The Procambarus genus comes from America, so it’s entirely possible there are many more species available in the pet trade in the states that aren’t available here in Europe.

Thanks! The problem about identifying the “swamp crayfish” is that it was a feeder lobster from petco, so is difficult to truly identify. For all I know it could be wild caught or cross-bred between masses of different species. Or it is a swamp crayfish, just not bred for color.
I’d also assume it’s not an asexual breeder like marbled crayfish, as I think I’ve read that marbled crayfish are all female, and all give birth without a partner, which my brown crayfish was probably trying to do with the blue one.

Update:
Whelp, after moving around some rocks looking for the disappeared lobster, it turns out she did, indeed, breed and now has eggs. If those eggs will hatch is beyond me. I feel bad for the father, who was moved to a different tank where he unfortunately was devoured . But, I will definitely keep you all updated, and who knows what the babies could look like?!

Update #2:
I found this little guy when cleaning the tank!

How big is it?

As of now, I’d have to say it is about 1/4 inch. Any idea how fast it will grow?