HCA: Hermit Crab Association

Hi, I am getting some fiddler crabs soon. I already have a large exo terra breeding box. Would that work? I would do half water half land with brackish water. Would putting in an air pump keep up humidity? Thanks!

The exo terra breeding box is probably 5 gallons. Is that enough space for 2 or 3 fids? It is made of plastic. Will the humidity be good if I cover the top?

Probably. I have 2 heated pools in my 55 gallon crabitat that make up less than a quarter of the surface and my humidity is pretty steady at 95%. I have air pumps blowing air in there constantly just to dry it out a little.

The large breeding boxes are just a little over 4 gallons. Maybe a pair of females could work in that, but I would be wary of putting in a male and female because they can get rather aggressive when it comes to mating and any female would need to be able to get away from him if she felt the need. A male by himself would get kind of lonely, and two males would outright kill each other. They will get large as they become full grown, and hopefully in two or three years you'll have a crab the length of your palm so please keep that in mind. My male that I bought as a baby and have had for a year is about that long, but he hasn't completely bulked up yet like they do when they get on in years.

For a container that size I would recommend constructing a platform where they can get out of the water and have a good land section (with substrate, since they wiil dig) and then the entire bottom of the tub could be water. Doing a slope in something that small isn't going to offer them enough dry land or enough water for even one crab, and will be very hard to keep clean and sanitary. It does need to be filtered water same as you would for a fish tank, so there's that to consider as well it's not going to be easy to fit a filter onto one of those breeding boxes since they're so shallow. You may be able to find a small internal filter (like a Tom Dive) that would work, but remember that the entire thing has to be sealed against escape so it'll have to fit inside entirely you'll have to get creative with securing it.

Humidity isn't such a major need with these guys since they do spend so much time underwater, and if you're going with true fids then they're native to the states and they won't need high heat or tropical conditions. Red Clawed crabs aren't fids and have slightly different requirements, so make sure to decide on a species before you set up their home. Fids should be kept in true brackish (using a marine salt) and also provided with a freshwater source as well. I have a large flat bowl for freshwater that's large enough for a few to submerge at a time and there's always a crab soaking in there.

I wrote up a little guide for Callalily's son here that covers all the basics: viewtopic.php?f=55&t=88451#p825939

There's also the entire evolution of my 29 gallon brackish fid tank here, with what worked and what didn't. Bit of a read, though, so if you have questions, ask away! : viewtopic.php?f=55&t=80873