Hi, I came up with a better way for finding out how many hermit crabs you should put in the tank. Basically, instead of using gallons, you find the area of the bottom of the tank and give 6 square inches to each hermit crab. Yeah, hermit crabs aren't 6 inches wide but it's good to have at least 2 inches of space between the molting crabs. So, first you find the length and width of the bottom of the tank and find the area. If you're using a standard ten gallon, that would be 20(length), and 10(width), and the area (length x width) would be 200. Then, since you give 6 square inches to each crab, you find the area of a 6 by 6 inch square, 36. Lastly, you do 200(area of bottom of tank) divided by 36(space for one crab) and you get 5.555555555555555. Round it down to 5(besides, it's good to have half a crab of extra space) and you have it. 5 crabs for a 10 gallon. This is for molting space, but you also have to use common sense. If your tank is very shallow, you should probably stock less because of climbing/exercise space lost. Also, you don't have to use 6 by 6 inches, you can go more or less, I just thought it was a good amount of space per crab. Anyway, hope you like it. If you find any messups or whatever, please tell me. Also, see if it works for your tank. I just want to see.