Capt. Kirk,my Blue-Tail,is thriving in a 5gal..just make sure you have a sandy bottom(approx. 3 cm.) with a scattering of small pebbles,some kind of hollow or rock-cave..and bear in mind,they will shred any plant you put in the tank,real or fake..avoid at all cost,putting any other fish with them,as they will kill them eventually..and I'd think twice about putting more than one Craw-fish in the same tank(no matter the size of the tank) because even though when they're young they can co-exist peacefully,when they get older sooner than later,they will fight to the death until you may or may not be left with a sole survivor....oh yes,make sure the tank you keep it in is covered at all times,because Craw-fish are extremely agile climbers,and are constantly climbing up ornaments,plants,and filters to break out and go exploring(hence the name of my clawed fellow..he actually escaped a holding tank and was skittering all over my apartment for over an hour with my poor girlfriend trying to catch him,when she decided to give his tank a clean one day while I was at work!)..he survived that little jaunt quite well and is still in his tank trying to climb out even while I type this!
Because I live in the Tropics where the average temperature is 30-degrees Celsius,I can't answer your heater question,but I can certainly tell you Crawfish need very good aeration in their tank or they will die(which is why Capt.Kirk continues to astound me with his hour plus out of water without perishing!)..a couple more things I should tell you,they have small stomachs,so you can feed them once every two days a varied diet of crab-pellets,waterweed,and thin slices of pumpkin,potato,celery(including leaves),and apples..just be sure to scoop out any leftovers after a couple of hours...the other thing is they go through a moulting process periodically where they shed their entire exo-skeleton(including claws!),which might leave you thinking you're looking at a dead crawfish when in fact it's hiding in whatever cubbyhole you've placed in the tank for it..leave the shed exo-skeleton in the tank as it's an invaluable source of calcium for all Crawfish and actually helps them grow a new exo-skeleton faster..from my experience,they tend to get quite hyper a few days before moulting and then go into a funk where they're not eating and hardly moving inside their hidie-hole,as long as you have adequate air going into the tank,don't worry it's not dying,just going through the moulting process as it continues to grow..and I can't overstress the need for a covered tank because they are inquisitive little buggers!
Ya thanks, you do know that that is a very good idea to scoop uneaten food out as they love to hoard and hide any uneated food, one thing I know. How big is yours right now, my petstore has some right now that are 3" large and I'm thinking that they would be too big for anything smaller than a 20 gallon tank.
Capt. Kirk is about 4"..If you have the space for a 20gal. for yours,I say go for it..I,unfortunately,don't have any more space in my apartment for a tank that big,especially since I'm seriously considering putting back in a second 55gal...in his 5gal. tank,he seems to be quite happy,and is more into climbing up his plants and ornaments.