Stocking For 15g. Crab Or Crayfish? Please Comment

[raptorrex]

I did my research on a cray because a friend of mine and I saw one when we were window shopping in fish stores together a couple days ago. Plus of course I was interested in possibly putting them in with a new tank I'm in the process of cycling. He ended up buying one, I didn't and came here to get advise instead. I can say that the advice was pretty accurate. The thing is AGGRESSIVE. It even tries to pinch him when he reaches into the tank, charges people from its little rock cave when they get near the tank, gnashing it's pincers and generally acting grumpy at all times. It makes a threat display whenever anything gets near his hut. Al has lost fish, I can't remember which ones offhand, if you feel it's important I'll ask him.

His was listed as an Australian Blue Lobster, in case that helps. Since I can see some appear to have had no trouble with cray, perhaps it's this particular species.

sounds very like a Redclaw, another common name is "Blue Lobster" Latin is [size=-1]Cherax quadricarinatus [/size][size=-1]or Cherax Quad for short. they are a tropical Cray, the only one that has been found so far, temps should be between 76 and 84, the upper temp is for breeding only. i would suggest 76-78. they need a high O2 environment. you say "he" have you sexed the critter? this is quite easy after they mature, seven months give or take, males tend to be Blue with red patches on the outside of the pincer, females are just as blue but with no patches. the gravel and the amount of natural light all have effect on the colour, so you see Redclaws that are green with red and purple spots and flashes. sadly there is no, known, way of telling the age of Crayfish. size is no guide, so unless you have it from hatching, first thing you will know is when the Cray starts turning blue, and the male gets its patches. this will indicate it is "mature" (seven months).

not all Redclaw are sociable, some are just plain grumpy, the one you mention sounds like one of these. quite what happens to this type of Redclaw, these Cray are, in the main, chilled indeed LAZY, is unclear, but putting immature Cray in a tank with fish will, without doubt, result in a grumpy and violent Cray, that will attack fish at any opportunity. not come across too many that attack their keepers though, unless you get too close, indeed many types of Cray can be hand fed, though this is something you need to work on.

even if your cray is not "fish safe"lol, they make cracking stock. they are acrobatic, fearless, fascinating and frustrating all at the same time.
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another hint here. if your Cray is trying to escape, the most common cause is low water O2. the only reason for a Cray to leave its water, is to find somewhere better!

 

[Seed]

sounds very like a Redclaw, another common name is "Blue Lobster" Latin is [size=-1]Cherax quadricarinatus [/size][size=-1]or Cherax Quad for short. they are a tropical Cray, the only one that has

This one is Cherax teniumanus, not the red clawed variety that you speak of. I've actually seen those for sale at a new fish store I visited over the weekend, and this guy is different. Its claws are blue, the entire organism is mostly blue with a white underside. He has a slight purple tint to his carapace, but it's hard to tell if its just the lighting or if indeed he is a little purple. Also, I have not sexed it, or even tried as it doesn't belong to me.... I think I call it a "he" because of his aggression. It just seems like a "he," if that makes sense. Honestly, it is striking, and I've never seen anything like it, aggression-wise. It apparently LOVES his hut and will not tolerate anything getting near it. Al's tank is a 75 gallon and is well aerated. He uses gravel with an undergravel filter (I like sand personally) and a two back mounted filters. The powerhead on his undergravel has a suction for air, and aerates the water quite well. The animal is about 6 inches in length, or about 15 cm.

I think the thing is just a grump. I'll mention it to him about being able to hand feed them, but I want to be at his place the first time he does it because I suppose it would be the very height of hilarity to watch him get pinched trying.

 

[raptorrex]

sounds very like a Redclaw, another common name is "Blue Lobster" Latin is [size=-1]Cherax quadricarinatus [/size][size=-1]or Cherax Quad for short. they are a tropical Cray, the only one that has

This one is Cherax teniumanus, not the red clawed variety that you speak of. I've actually seen those for sale at a new fish store I visited over the weekend, and this guy is different. Its claws are blue, the entire organism is mostly blue with a white underside. He has a slight purple tint to his carapace, but it's hard to tell if its just the lighting or if indeed he is a little purple. Also, I have not sexed it, or even tried as it doesn't belong to me.... I think I call it a "he" because of his aggression. It just seems like a "he," if that makes sense. Honestly, it is striking, and I've never seen anything like it, aggression-wise. It apparently LOVES his hut and will not tolerate anything getting near it. Al's tank is a 75 gallon and is well aerated. He uses gravel with an undergravel filter (I like sand personally) and a two back mounted filters. The powerhead on his undergravel has a suction for air, and aerates the water quite well. The animal is about 6 inches in length, or about 15 cm.

I think the thing is just a grump. I'll mention it to him about being able to hand feed them, but I want to be at his place the first time he does it because I suppose it would be the very height of hilarity to watch him get pinched trying.

where do you live? i am unsure here the description of colouration, is not even remotely the Marron, especially a blue one, it is pure Redclaw. that is not to say it is a redclaw, just the description suggests that. Blue Marron are blue and white, apart from and algae it may grow. the Blue colour is a genetic defect, like Ginger hair in humans. but its worth remembering, that if it is a Marron it is best not kept at tropical temps, not that it cant live in them, just it will suffer from the low O2 and will be very open to bacterial infection. a picture would be good. not for ID, i just love looking at Crayfish.

 

[Seed]

sounds very like a Redclaw, another common name is "Blue Lobster" Latin is [size=-1]Cherax quadricarinatus [/size][size=-1]or Cherax Quad for short. they are a tropical Cray, the only one that has

This one is Cherax teniumanus, not the red clawed variety that you speak of. I've actually seen those for sale at a new fish store I visited over the weekend, and this guy is different. Its claws are blue, the entire organism is mostly blue with a white underside. He has a slight purple tint to his carapace, but it's hard to tell if its just the lighting or if indeed he is a little purple. Also, I have not sexed it, or even tried as it doesn't belong to me.... I think I call it a "he" because of his aggression. It just seems like a "he," if that makes sense. Honestly, it is striking, and I've never seen anything like it, aggression-wise. It apparently LOVES his hut and will not tolerate anything getting near it. Al's tank is a 75 gallon and is well aerated. He uses gravel with an undergravel filter (I like sand personally) and a two back mounted filters. The powerhead on his undergravel has a suction for air, and aerates the water quite well. The animal is about 6 inches in length, or about 15 cm.

I think the thing is just a grump. I'll mention it to him about being able to hand feed them, but I want to be at his place the first time he does it because I suppose it would be the very height of hilarity to watch him get pinched trying.

where do you live? i am unsure here the description of colouration, is not even remotely the Marron, especially a blue one, it is pure Redclaw. that is not to say it is a redclaw, just the description suggests that. Blue Marron are blue and white, apart from and algae it may grow. the Blue colour is a genetic defect, like Ginger hair in humans. but its worth remembering, that if it is a Marron it is best not kept at tropical temps, not that it cant live in them, just it will suffer from the low O2 and will be very open to bacterial infection. a picture would be good. not for ID, i just love looking at Crayfish.

I live in California, USA. The scientific name is what it was billed as at the fish store where we saw them on display. At a different store we saw crays displayed as the red-clawed variety, and they were different in the shapes of their crushing claws; they were thinner/more pointy then the others. Their coloration was different as well. The red-clawed variety had a slight orange/red tinge to their claws and parts of the body as well, in a fashion completely different to what we saw at the other pet store. What Al ended up getting has no red coloration of its claws at all and is only very slightly purple along the sides of the main part of its body (forgive my lack of correct terminology to describe this). The purple color is so slight that I can't even be certain it is there, it could possibly be a trick of the lighting.

EDIT
I don't have a digital camera BTW so I can't do pictures yet. I plan on buying one in the near future, if you are still interested at that time, I'll put up pictures.

 

[raptorrex]

I live in California, USA. The scientific name is what it was billed as at the fish store where we saw them on display. At a different store we saw crays displayed as the red-clawed variety, and they were different in the shapes of their crushing claws; they were thinner/more pointy then the others. Their coloration was different as well. The red-clawed variety had a slight orange/red tinge to their claws and parts of the body as well, in a fashion completely different to what we saw at the other pet store. What Al ended up getting has no red coloration of its claws at all and is only very slightly purple along the sides of the main part of its body (forgive my lack of correct terminology to describe this). The purple color is so slight that I can't even be certain it is there, it could possibly be a trick of the lighting.

EDIT
I don't have a digital camera BTW so I can't do pictures yet. I plan on buying one in the near future, if you are still interested at that time, I'll put up pictures.

as you say, the Redclaw has slimmer, more pointed claws than the Marron.

this is a young female Redclaw:

this is a mature, though very young female Redclaw notice the Blue that is now on its claws:

this is a mature female:

and a mature male:

and for interest a mature "Pink Morph", not often seen, male:

now this is big, but this is the natural colour of a Marron:

this is a "Blue Morph" Marron, notice there is only two colours here, blue, and shades, and white.

 

[Seed]

You know, after looking at your pictures I'm not sure what it is now. The claws of both species you just posted are different than this. The red-claw is completely different, even the rare pink male which is the closest. The marron's claws are different as well. They are way too smooth, this guy has little spikes all down the length, and the first segmennt of the arms of the claws look so much thinner. The claws of both are just shaped very differently.

I'll see if I can get a picture ASAP because this has got me very curious now.

As far as the pet store goes, I did a review on it in the U.S. directory, it's the Pet Connection entry, a crappy store, and I wouldn't put it past them to completely mislabel a species.

 

[raptorrex]

You know, after looking at your pictures I'm not sure what it is now. The claws of both species you just posted are different than this. The red-claw is completely different, even the rare pink male which is the closest. The marron's claws are different as well. They are way too smooth, this guy has little spikes all down the length, and the first segmennt of the arms of the claws look so much thinner. The claws of both are just shaped very differently.

I'll see if I can get a picture ASAP because this has got me very curious now.

As far as the pet store goes, I did a review on it in the U.S. directory, it's the Pet Connection entry, a crappy store, and I wouldn't put it past them to completely mislabel a species.

ahh there is a smooth Marron:

sorry forgot to post this one.

want to see a monster?

bit hard to see, but the one on top is a "normal" redclaw, about six inches and 90gm. the one below, covered in algae, is close to 900gm, and still going strong. lol and no they are not mating or fighting, all cray and fish move towards the "big un" if people come into the room or, there is a disturbance in the tank, behaviour that is not unusual in a Cray community tank. well those that work anyway.

I forgot to credit the pictures that i did not take in my last post, so: thanks to Paul (Crusty), Crayindo and a firm that sent me the pic of a male Redclaw i was thinking of buying, sorry cant remember who.

 

[Seed]

That's awesome. Your pictures are inspiring me to want to set up a cray tank. While it's a ways down the road, do you have any advise on how it should be done, i.e. tank size, compatable non-cray species, etc?

 

[raptorrex]

That's awesome. Your pictures are inspiring me to want to set up a cray tank. While it's a ways down the road, do you have any advise on how it should be done, i.e. tank size, compatable non-cray species, etc?

I would be glad to help, if i can.

tank size remain fairly constant, roughly 20ukg per cray (kept on its own), though some North American Cray are reported to do ok in 10ukg. i would say, personally , about 30ukg. its surprising how small a 3 foot tank looks when the Cray has grown to 6 or seven inches, remember that is nose to tail, you need to add 3 to 4 inches for the claws and the antenna are the same length as the body!

so, a 20-30 gallon tank, Gravel of any size from Peagravel to 1/4 inch is fine. lots of caves and hides, even for only one Cray. NO live plants, they get destroyed in quick time. a platform for the Cray to sit on that is not more than 300mm below the surface of the water, not really sure why on this, but it comes up time and time again when researching Cray keeping. my guess is its down to the O2 content of water in deeper tanks. a high O2 content, so the filter outlet at, or close to, the surface of the tank. airstones are a fev toy of may Cray so 1 or 2 of them will go down well. a well secured lid, Cray are adept at escape, though it is often lack of O2 that causes these escapes. For a Redclaw you need a heater, temp between 78-84f. most other Cray will do better without.

Feeding, often forgotten but very important, Crayfish are not predators or carnivores. they are low level omnivores, their diet needs to be, when mature, mainly Vegetables, with the odd treat of meat/protean. never never try to feed your Cray Feeder fish, however the LFS tries to convince you to do so, it is very unhealthy, and totally unnecessary. there is no need to add Calcium or use calcium high foods. as Crayfish absorb the calcium they need through their shell, it happens at a constant rate, so, providing the water is of the correct Ph any addition is wasted.

Ph, well it goes according to the cray you keep. but between 7 and 8.5 is recommended, and covers most Cray. don't be too worried if you Ph seems low for your Cray, providing it is no less than 7 most will be fine, its the same for fish! though 7 is not your base for all of them.


compatibility with others is a thorny question. I kept my Redclaw in my community: plecos, cory, usd cat, gurami, angels, pictus cat, CAE, RTS, silver dollars, and so on, in short a broad spectrum of fish and tank levels, and lost only 2 bamboo shrimp, and i did catch her polishing off the dead body of an angel the Green Terror/ Blue acara killed. that said many put a Cray in their prized community, only to find lots of them dead after a short while! so i would say, initially, it is better to assume that NO fish are safe with a Cray. there is a thread that deals with how, I think, it may be possible to keep Cray in a Community, so a search with Cray and my user name may be worth a try.

lol i cant wait for the reaction to this . if you keep a Cray only tank, water changes are a thing of the past, you top of for evaporation, and totally clean the tank once a year, and that's it! I myself do not do this, it is however, the standard way to keep a Crayfish, throughout the world!

 

[Seed]

That's awesome. Your pictures are inspiring me to want to set up a cray tank. While it's a ways down the road, do you have any advise on how it should be done, i.e. tank size, compatable non-cray species, etc?

I would be glad to help, if i can.

tank size remain fairly constant, roughly 20ukg per cray (kept on its own), though some North American Cray are reported to do ok in 10ukg. i would say, personally , about 30ukg. its surprising how small a 3 foot tank looks when the Cray has grown to 6 or seven inches, remember that is nose to tail, you need to add 3 to 4 inches for the claws and the antenna are the same length as the body!

so, a 20-30 gallon tank, Gravel of any size from Peagravel to 1/4 inch is fine. lots of caves and hides, even for only one Cray. NO live plants, they get destroyed in quick time. a platform for the Cray to sit on that is not more than 300mm below the surface of the water, not really sure why on this, but it comes up time and time again when researching Cray keeping. my guess is its down to the O2 content of water in deeper tanks. a high O2 content, so the filter outlet at, or close to, the surface of the tank. airstones are a fev toy of may Cray so 1 or 2 of them will go down well. a well secured lid, Cray are adept at escape, though it is often lack of O2 that causes these escapes. For a Redclaw you need a heater, temp between 78-84f. most other Cray will do better without.

I will be doing this sooner than I thought. A week ago I bought a 20 gallon tank that I am cycling. With the fishless method touted here, it is nearly done after a week, which just amazes me. If it happens to outgrow the tank, it's a simple thing to hop onto Craigslist.com and find larger one for very cheap. I really tend to like using sand, do you think that sand is appropriate for crays? It seems like it should be, but I'm not sure.

Another question.... how much does it hurt to get pinched?

Feeding, often forgotten but very important, Crayfish are not predators or carnivores. they are low level omnivores, their diet needs to be, when mature, mainly Vegetables, with the odd treat of meat/protean. never never try to feed your Cray Feeder fish, however the LFS tries to convince you to do so, it is very unhealthy, and totally unnecessary. there is no need to add Calcium or use calcium high foods. as Crayfish absorb the calcium they need through their shell, it happens at a constant rate, so, providing the water is of the correct Ph any addition is wasted.

What specifically do you feed them? Prepared foods like spirulina discs, fresh vegetables, and if so, what vegetables work out the best?

lol i cant wait for the reaction to this . if you keep a Cray only tank, water changes are a thing of the past, you top of for evaporation, and totally clean the tank once a year, and that's it! I myself do not do this, it is however, the standard way to keep a Crayfish, throughout the world!

It is an excellent reply, you honestly ought to edit it up and put it in the invertebrates section.

I am curious about why water changes won't be necessary anymore? My friend's cray seems to poo like nothing I've ever seen before.

 

[raptorrex]

I really tend to like using sand, do you think that sand is appropriate for crays? It seems like it should be, but I'm not sure.

Another question.... how much does it hurt to get pinched?

sand will do, though if you can come up with a mixed bottom, humm sounds like a line from a "carry on" film, perhaps better. it depends on the Cray but if they burrow, sand makes it difficult.

yes it does, its been known to draw blood. but in the main that's not so bad as their escape reflex. when cornered or picked up, Crays tend to bend double, then snap their tails back. this creates massive push in the tank, giving the lie to the fact Cray are slow. but if it happens out the tank, even a small Cray, can be very difficult to control.

What specifically do you feed them? Prepared foods like spirulina discs, fresh vegetables, and if so, what vegetables work out the best?

i use fresh, well Birds Eye, peas. pop the skin off before putting them in the tank, else it causes such a mess. cucumber (don't peel or cut, just wash and snap) carrot (more on that later), algae wafer, oak leafs (a great favourite) and if i am strictly honest, any "Quality", Cray specific, commercially sold foods. add some fish flake, daphnia, or even fresh cooked chicken, as the treat and protean requirement.
carrots, potato and the oak leafs need to be, how you put it? rotted before they are eaten. another benefit of a Cray only tank, is you can add the veg, and let them rot in the tank. the cray will then polish it off.

I am curious about why water changes won't be necessary anymore? My friend's cray seems to poo like nothing I've ever seen before.

well it seems Crayfish do not react to nitrates in the same way as fish, in fact they don't seem to react to it at all, till it makes up most of the liquid they are living in. probably come from the fact that they are detrivors, they eat rotting matter, wouldn't do to be sensitive to the products of degeneration, if you eat it to live. I admit that this is so alien to me i don't do it, but it is without doubt a very effective, and perhaps a tad more natural than our usual methods.
Cray can live quite happly in water you cant even see through, providing it has a high O2 content, even a muddy field is crayfish heaven.

 

[Seed]

Thanks for all that. One last question about feeding. How much and how often should they be fed generally?