Clicking noise coming from my tank?

[Tank-Jewel125]

I've not long set my first jewel 125 up. I has various fish, shrimp, crabs, snails, one starfish, and one slug, see pictures.. Recently I've noticed a loud clicking noise I believe coming from a crab, I don't believe it's the hermit crabs as they were my first and I have only recently noticed it. What could it be? It tends to happens when the light has been switched off, but does occur when the light is on???,

 

[jay0705]

Have u added any new live rock?

 

[deejeff0442]

Either a hitch hiker mantis shrimp or if you have a clown like a tomato they make a clicking noise

 

[jay0705]

Thats my thought is a mantis. You have there food in hermits and snails. The clicking is them hammering on a shell

 

[pegasus]

Is it a clicking... or perhaps a "popping"? You may have a pistol shrimp, which makes a popping noise to scare off anything they might consider a predator. They sound identical to a mantis. Just a thought...

 

[geridoc]

Keep your fingers out of the tank until you rule out a mantis

 

[jay0705]

Lol there fine I have 2

 

[gemmy]

I'm thinking it is a pistol shrimp. If fish start disappearing along with your CUC, I would change that to a mantis.

 

[jay0705]

Mine don't touch fish, cuc crew yes. I started adding hermits for that reason lol