2. Do you have gauges in the tank to measure temperature and humidity? If so, where are they located and what temperature and humidity do they usually read? Side of tank, 75/75 about- in yellow
3. Is a heat source used in the tank? If so, what? Fluker's UTHs
4. What types of water are available (fresh or salt) and how is the water treated (what brands of dechlorinator or salt mix and what ratio is used to mix it)? Salt from bottle & fresh
5. What kinds of food do you feed and how often is it replaced? Powder, eggshell,veggies/fruit every couple days
6. How long have you had the crab and what species is it, if known? Since Sept 2015, PP
7. Has your crab molted, and how long ago did it happen? Crab went down 3 wks ago. We're a bit unsure which is down as they change shells and are same size. One was down 2 + months, Husband thinks he didn't finish because his color didn't change so he went down again almost immediately (maybe a few days to a week later). If it was the other one, Hermie then he molted pretty quickly around October 2015.
8. What type of housing are the crabs kept in, what size is it and what kind of lid is on the housing? 20 gal, glass lid
9. How many crabs are in the tank and about how large are they? 3 total. 1 is in ISO molting, 2 small share big tank, the one I'm writing about is 1 of the 2 in the big tank
10. How many extra shells are usually kept in the tank, if any? Maybe 7
11. Have there been any fumes or chemicals near the crabitat recently? No
12. How often do you clean the tank and how? Spot clean every other week. Bowls etc more often. Just put new sand etc in 3 wks ago when they were moved to 20gal from a 10gal (that I thought was a 15gal)
13. Are sponges used in the water dish? If so, how are they cleaned? 2. Every couple months or so.
14. Has anything new been added to your crabitat recently? Yes. Fake plants, play sand/coco fiber, plain untreated wood shelf.
15. Is there any other information you would like to share that might be helpful (anything that is regularly part of your crab care, playtime, bathing, etc.)? No
Situation:
Ok I have smelled dead things before so just wanted to check in on my tank's fishy smell. It's not a gross dead smell, just fishy. I have a healthy little crabbie up and about but the other little went down a few weeks ago. Not long in molting terms. But the tank and things in it all have a fishy smell that's not more than a day or two old. It's strong enough to make my hand smell just from handling a shell. I also keep the moss on a medium size plastic lid and other hermie pushed the lid on top of the area of our molter. So I wonder if the lid atop of that spot for maybe a day or two could've suffacated little Hermie down there (though it's a 20 gal tank). Could the fishy smell be from a molter who has died beneath the sand? Where else could the fishy smell be coming from?
I have another medium size molter in another tank Who's been down since Dec. We're waiting for him to resurface also - though no smell in there.
Despite all the challenges with heat & humidity & A panic over Tiny molting for an extended period, we've managed to keep these little guys alive and well since Sept. I'd be heartbroken to lose Hermie now now that we finally got all the conditions and a larger tank humming along (thanks to advice from this site and Fluker's heating pads).
Thanks guys!
that's great news! Did you figure out the mystery smell? Eh, who cares about that though! Your crabby is okay! 
