I have a heater in both tanks (main and breeder). Temp stays at 78 in the breeder and about 81 in the main tank. I've had the temp a little higher (83 to aid in controlling ick) in the main tank when I did a tank swamp. The crays seemed to have no problem and I left it like that for like a month. I never heard of such a thing of not being able to use a heater. My main tank is low-brackish (ie its got salt for the mono, scats, and archer) as well, yet the crays do just fine in it (crays are freshwater).
I have read that they shouldn't be kept with other fish BUT I feel thats more of a warning. It comes down to what kind of fish you have. Not all fish would be the perfect tank mate. I've got them mixed with fish. Heres the fish that I have:
3 silver dollars, 1 mono, 2 scats, 2 clown loaches, 1 archer, 2 kribs, 1 pictus cat, small royal pleco, and a big common pleco.
The breeder has a few small fish that I got for free. Zebra danio, tiger barbs, and some all white fish. Probably some kind of tetra. Anyways, they don't bother the little guys at all.
The cloan loaches do get grabbed sometimes because they tend to be lazy and just lay around. Makes them an easy target. The pleco's sometimes have issues but they are pretty tuff. My pleco's are pretty active throughout the day so its not really an issue. There are some plecos that hide all day (are active at night), those will get grabbed if hiding on the bottom. The crays walk around and if they come up to a fish just laying there, well you get the idea.
Just stay away from bottom dwellers and go with active non-aggressive fish. Yes theres always that chance, thats why you be careful with your selection choices.
I'm not sure off hand how big they get. Might want to search for that info. I think its something like 3~4" but don't remember.
Ok so it sounds like we're going to be in Michigan not this weekend but the following weekend. In the mean time, I need to do research on these guys and make sure that I know my stuff before bringing one home.
I have read that they shouldn't be in a heated aquarium, shouldn't be kept with fish (unless you don't mind them disappearing), and that they should only be kept one per tank. I have an empty 10 gallon tank right now that I might use, but I'm not sure yet it that would be big enough for one or two. Also, that tank has a preset heater that usually stays around 76 degrees but I have noticed that it gets up to 80 when I don't have the AC running. How big do they get?
If you could give me some information that would be helpful, I'd really appreciate it. I figure that you know your crays!