Hi all,

I will answer the emergency questions below. The HCA forum won't let me register an account right now, but I would like to post there too. TL:DR I found a sunken in black spot on my crab today and I am very concerned about black spot disease/shell rot and would like help confirming that issue and how to proceed. 

1. I have a 100g aquarium with hinged glass lids. 

2. \~10" of substrate (eco earth and playsand mixed at the appropriate portions/until it has the correct texture to hold tunnels). 

3. AcuRite hygrometer suspended in the tank to obtain most accurate readings. Heat stays around 80° (3 heat mats throughout tank) and humidity around 75-85% (with a bubble pool and 2 moss pits). 

4. 3 heat mats (1 small zoo med mat on the tank end and two large mats from Bean Farm, recommended by LCHOS). 

5. I have two moss pits, I use sphagnum moss from LCHOS approved sellers. 

6. I use tap water treated with prime conditioner. For salt water I use instant ocean. They have a deep pool with salt and freshwater sides, bubblers, and stairs in/out. 

7. I have 6 crabs. Two are quite large (maybe jumbo?) the rest are medium-large. 

8. Photo included. I provide as much vertical enrichment as I can, lots of hides, natural objects (lotus, cholla, bark, leaves) etc. 

9. Varied diet, all food is from LCHOS, with the exception of fresh fruit and veggies. They always have access to greensand, crab shell, etc. and a mix of protein, calcium, and fat sources, along with foraging products (ex. lotus pods) and fruit/veg/seed mixes. I do not feed fresh seafood and all shellfish is dried / from LCHOS approved sellers. 

10. I only move them as needed for enclosure maintenance and avoid handling. A couple weeks ago they moved houses (3 hour drive) and seemed to do well in their critter keeper during the move (remained active, curious, etc.).

11. I currently have 6 crabs. Most recent adoption was \~4 years ago from a LCHOS member. I adopted my first crab 7 years ago (emergency rehome), then adopted 2 friends from LCHOS shortly after for him, then adopted 5 more a couple years after that. I currently have 6 crabs. I lost one during a molt a year ago (unknown cause, found empty shell buried). When I had to empty the substrate to move 3 weeks ago I found another molter had passed (again, unknown cause). They all have appeared healthy, happy, and active, and undergoing normal molts. So I don't know why those two passed. I increased the protein and calcium i was feeding after the initial molter passed, and provided more varied sources, just in case that was the issue but I truly don't know. 

12. I have a "shell shop" with a wide variety of turbo shells available (preferred shells). I always have at least a few shells bigger than my biggest two (jumbo, 0.25-0.5" bigger) and then lots of large and medium shells for my others, including smaller sizes if they ever decide their current pants are too big. 

13. No fumes or chemicals.

14. Fresh food and water, cleaning up any moldy food etc. But otherwise I minimally bother them, occasionally change enrichment/decor and fix anything they knock down as needed. 

15. As described, I lost two molters in the last year. I have no idea why because everyone appears happy, healthy, active, colorful, and they have a wide range of food and supplements available. When looking at them today, I saw a recessed black spot on a crab. I am very concerned it is shell rot / black spot disease. I watch the crabs closely and often and checked over all the other crabs. I did not see anything on the others. I did not see anything on the two molters that went down and didn't come back up. I do not ever feed fresh seafood or meat. The only shellfish I feed is dried and from LHCOS sellers. I have no idea how shell rot would have been introduced? I am hoping for information on how to proceed, if this looks like shell rot, and if it is treatable at all. I know to quarantine this guy, but do I throw out all their food and replace it? Should I find an exotic vet?  I love my crabs so much. I strive to give them the absolute best life possible and I feel terrible about this. 

I appreciate your help. I also want to post on HCA forum but it wont let me register a new account, if anyone here can help with that, please let me know. 

Thank you 💓🦀

Potential shell rot/black spot disease? Please help (not graphic)