Diamond Watchman Goby died or killed

[salt_for_brains]

More than likely it is walking and not detaching and attaching again. If it is moving that much it is very unhappy with flow, lighting, water, safety or all of the above. Monitor it as closely as you can for gaping mouth, staying shriveled up, not attaching anymore, or worst case deterioration (remove immediately) because if it starts coming apart in your tank it can cause a huge ammonia spike.
Like little_fish said your tank is a little young for anemone. Sorry I didn't even notice you had an anemone in your earlier post.

 

[Pysiek]

Thats what I was worried about. But the guy at LFS told me it should be fine with it.

 

[Pysiek]

I do not want to kill the anemone . I have to find somebody with matured tank who will be able to hold it for me.

 

[FishyReef]

Thats what I was worried about. But the guy at LFS told me it should be fine with it.

Yeah, unfortunately employees are often more interested in making a sale than really checking out whether your tank can support a particular animal. I can't tell you the number of people here who have had similar experiences (myself included). I'd suggest either finding a local reefer who can take it for you, or returning it to the store.

 

[KelliZackMOM]

I'm gonna share my experience with a diamond watchman goby and clowns. I had my goby for a few months and he sifted all over the tank then as soon as I added my pair of ocellaris he began hiding in his cave all the time. I never saw any bullying but I assumed maybe the clowns got after him once when I wasn't looking and that was enough to make him hide. At feeding time he would come out and grab 1 or 2 bites of food and then back to cave. This went on for 2-3 weeks and then I quit seeing him at all. Poor guy starved to death I assume. I never did find his remains, my CUC took care of that.
It may have very well been your clowns even though you never actually saw any bullying. I think these type of gobies are very timid and one nip could have drove him into hiding. OR he may have just been sick and died, sometimes no matter what you do that happens.
My female ocellaris is meaner than mean to me. If I am near the tank she follows me around just waiting for me to stick my hand in so she can attack. Cleaning the tank at my house is now referred to "gonna go fight Penelope(yes, I name my fish)". I have black ocellaris which I think are considered semi-aggressive and can be meaner than the orange ones, but all clowns I think have the tendency to attack even if they are considered peaceful. Peaceful, maybe if no one invades their space.

 

[Pysiek]

I do have a Kaudern's Cardinal and when I feed the fishes Cardinal a lot of times grab the food faster then the clownfish and then female start to byte cardinals tail and chase him.
So I do believe clownfishes might be aggresive when somebody is approaching theirs territory