What's killing my fish and crab?

[Darryn Lyon]

Hey everyone, New to the form here. My wife and I just got a new saltwater aquarium on Saturday. We got a 32 gallon bio cube, which is a great beginner setup. We got a bunch of live rock, 5 hermits, a cleaner shrimp, and added 2 small clownfish yesterday.

This morning, one of the clownfish disappeared for quite a while, and surfaced later dead. Now one of my hermit crabs looks like it got attacked or something, his claws are laying near him, with the clownfish nibbling at them, and I see him moving a little bit but I think he's just about dead. Could he be just shedding? Last night we also discovered that in some of the live rock we got, we have at least one brittle starfish that was hiding inside, and probably 2 or 3.

Cleaner shrimp don't do this, do they? Could the clownfish have? The starfish? I'm kind of puzzled, it's like a murder mystery.

I'm sorry, it's my first tank and I'm very new to all of this. Thank you very much in advance for all of your help!

 

[Tahoe61]

Hi and Welcome.

Aquariums need to establish a biological filter that breaks down organics/waste. If a tank has not been allowed to adequately cycle ammonia builds up kill tank inhabitants.

Test for ammonia, if you see a detectable level than you can either proceed with a small water change and or use Prime.

 

[dbl]

Welcome to R2R. I agree with above.

 

[Grey Ghost]

Are you absolutely positive on the species identification of the shrimp? Some banded coral shrimp species or pistol shrimps can be somewhat territorial in small aquariums.