Hermit Crab Help

[ronald]

I've had my tank going for quite awhile now and everything has been perfect.
A couple of weeks ago one on my 5 Hermit crabs died. I didn't notice right away (I figured he was molting) when I picked up the shell he was dead (and STINKY). I took him out and checked the levels of my tank.... The nitrates were about 40. I did a 30% water change. Since then 3 others have died, the most recent today. The nitrates are about 5. I don't understand what is killing these crabs. They are fed well, with leftover silversides from our Lionfish.
Anyone have any ideas ?

 

[beth]

I'm assuming that your ammonia and nitrite levels are zero, and that's why you didn't mention it?
Invertebrates, unlike fish, have little tolerance to nitrate. That is why your crabs are dying. If ammonia and nitrite are fine, then you can assume that your nitrate level is too high, and probably phosphates too. In the absence of a "reef" type filtration system, the only way to eliminate nitrates from your system, is weekly water changes, and a significant decrease in livestock load and feeding. Oh, and I assume you are using a carbon filtration system? If not, you need to.