HCA: Hermit Crab Association

I have been put in charge of taking care of the hermit crabs at work. They are in a fish tank with two bulbs in the top of the tank, no heater other than the light bulbs. It gets really warm amd humid in the tank with two light bulbs, so I took one out. They had gone without any bulbs for over a week and seemed to be very active. Do I turn out the light at night? It seems natural to do that.

There are four crabs in the tank. The largest one is in a shell about an inch and a half in diameter. How deep should the substrate be for the big one? They have not been bathed in months, but seem to be doing well. They have a great climbing structure that they use and several spare shells. They like to dig in and I am just learning about moulting.

I really want to take proper care of them as they have been neglected for some time. I was assigned the task because I kept finding their water dish empty. I have requested a humidity guage and anything else they need will be provided.

Thank you for any help and suggestions

First off, I see that you have requested a humidity gauge and that's great. Is there a thermometer in there now? The best way to determine how many lights to have on is by seeing how the temperature is affected by them since the lightning requirements vary from tank to tank. You should turn the lights out at night as long as the tank won't get too cold. Your temperature should be between 73-80 degrees for most species of hermit crabs (If you don't know the species, you could post pictures and someone here could help you identify them). If you do need a light on at night, they sell moonglo bulbs which give out the necessary heat but are not as bright. They are meant to simulate moonlight.

In general, the substrate should be about twice the height of the largest crab's shell. Also, what type of substrate is being used? If you use playsand, it should be moist to help them dig easier.

Bathing is not necessary as long as they have a water dish deep enough for them to submerge themselves up to their shell. Also, they should have a second water dish containing salt water. You would use marine salt made for saltwater aquariums not table salt.

Also, I know you mentioned some extra shells in the tank. You should ideally have about 3 extra shells per crab.

Sorry if I overwhelmed you with all the information. If you have any other questions feel free to ask.