Please help, what kind of fish is this? It ate my fish ?

[Kevin911]

I move rock around and didn't see anything.. how much you think this goby/ eel is worth at that size? I'm planning to sell or trade it for clown fish

 

[Jrob]

if you have a sump, look in the overflow box...my buddy had a clown get sucked into his overflow and stuck in teh back portion