Crab confusion

[perplexist]

I ordered 4 red claw red devil crabs off amazon. The next day they all died. I run a freshwater tank 60l at 25c and no surface area. I added blue velvet shrimp the same day. I did not acclimate either but only the crabs died. Is this due to no surface area and if so why? They breathe using gills so no surface area should not have been an issue. the temp was the correct temp for their species, and there was plenty of food. one had escaped later the day they arrivedd and i had to turn the tank inside out before i found him under a bag away from the tank. Is it possible that messing with the tank while they were still adjusting killed them? Is it possible that the one who escaped died first andd the others followed? Why are the shrimp doing fine? I also have triops in the tank who are doing fine as well. Id like to know because before they died, I had another order of crabs coming and id like to avoid killing them if possible. Also instead of surface area, Ive added the top of a jar to my tank with an air pocket. so hopefully that will help if the issue was really no surface area. Ive seen this done before.

[WV Reefer]

5 hours ago, perplexist said:

I ordered 4 red claw red devil crabs off amazon. The next day they all died. I run a freshwater tank 60l at 25c and no surface area. I added blue velvet shrimp the same day. I did not acclimate either but only the crabs died. Is this due to no surface area and if so why? They breathe using gills so no surface area should not have been an issue. the temp was the correct temp for their species, and there was plenty of food. one had escaped later the day they arrivedd and i had to turn the tank inside out before i found him under a bag away from the tank. Is it possible that messing with the tank while they were still adjusting killed them? Is it possible that the one who escaped died first andd the others followed? Why are the shrimp doing fine? I also have triops in the tank who are doing fine as well. Id like to know because before they died, I had another order of crabs coming and id like to avoid killing them if possible. Also instead of surface area, Ive added the top of a jar to my tank with an air pocket. so hopefully that will help if the issue was really no surface area. Ive seen this done before.

They need an area of land to survive. 

[king aiptasia]

11 hours ago, perplexist said:

I ordered 4 red claw red devil crabs off amazon. The next day they all died. I run a freshwater tank 60l at 25c and no surface area. I added blue velvet shrimp the same day. I did not acclimate either but only the crabs died. Is this due to no surface area and if so why? They breathe using gills so no surface area should not have been an issue. the temp was the correct temp for their species, and there was plenty of food. one had escaped later the day they arrivedd and i had to turn the tank inside out before i found him under a bag away from the tank. Is it possible that messing with the tank while they were still adjusting killed them? Is it possible that the one who escaped died first andd the others followed? Why are the shrimp doing fine? I also have triops in the tank who are doing fine as well. Id like to know because before they died, I had another order of crabs coming and id like to avoid killing them if possible. Also instead of surface area, Ive added the top of a jar to my tank with an air pocket. so hopefully that will help if the issue was really no surface area. Ive seen this done before.

like wv reefer said, they aren't fully aquatic and need to crawl out on land just like some species of crayfish or they drown