Dead fish and crab

[jrt9430]

I had a royal gramma and a porcelain crab for about 2 weeks and just found them dead. I have a 29 gallon biocube. I also have a blood shrimp, hermit crab, a snail and a bunch of blue hermit crabs that are just fine. Checked the water and everything seems fine. The only thing is my ph is a little off at 7.8-8.0 and nitrates at 40. Any ideas??

[Bectan01]

Nitrates at 40 could, that's pretty high for inverts. How old is the tank? If its a new tank there seems to be too many inverts they could be competing for food. Did the fish show any signs of illness?

[jrt9430]

Tank is about 6 weeks old. Didn't see anything wrong with the fish or crab. They were both eating fine.

[Bectan01]

Hmm, I would say the tank is far too young for all those invests, there will be not enough food for them to eat! Not sure about the fish, what are all the tank readings? Salinity? Ammonia? Your tank would have only just finished cycling (hence high nitrates) how did you cycle it?

[jrt9430]

Ammonia - 0
Nitrite - 0
Haven't tested for salinity
All other tests checked out ok. It cycled with live rock and did some pwc. The rock has some coralline algae growing on it

[Bectan01]

I would check your salinity. You should be keeping an eye on its levels every few days particularly when you've just set up a tank. do you use a refractometer? A hydrometer can give inaccurate readings. I take it there is no other fish in the tank and this is your first saltwater tank?

[jrt9430]

Yeah no fish since the royal gramma died. That was the only one. This is my first tank. I have been buying my saltwater from the fish store so I haven't purchased anything to test it

[Bectan01]

You need to test your own water, you may not know that as your water evaporates the salt doesn't so ever since you've had the tank the salinity is rising. You need to top of regularly with ro-di (plain, unsalted) water. This may be your problem. I top off twice a week on my 55 and 4-5 times a week on my ten.
Buy a refractometer off eBay and get that in check before purchasing any other livestock...

[jrt9430]

Ok thanks. I will get some water tomorrow. I will pick up a refractometer