Thankful for a cover

[Coralgurl]

Bought a Christmas wrasse today, my stupid clownfish is chasing it. The corner of my cover was slightly raised, the wrasse jumped into the emerg over flow. It's full of algae and grossness, must not have a lot of oxegyn in there as it swam back to the surface, was able to scoop him with my hand back into the tank. Hopefully everyone settles and leaves him alone soon!!

He is hiding in the corners at the top of the tank, nose up, should I be worried? I do have a sandbed.