Goby acting strange

[jam5971]

I have what was sold to me by my LFS as a sand sifting goby and he indeed sifts through the sand. From studying pictures I believe it to be a Sleeper Blue Dot Goby, Valenciennea sexguttata.
Normally he hangs around the bottom of the tank making the odd foray to the middle reaches of the tank and even to the surface. Before I went out this morning he seemed to be making more visits to the top of the tank than normal. When I came home tonight I initially couldn't see him but then found him at the top of the tank and appeared to be stuck to the intake of my weir Thinking there might be a problem I carried out my normal water tests even though the other fish appear fine. All came out ok. Switching off the pumps he went down in the tank briefly before returning to the top against the weir intake. On adding some mysis shrimp he took some and now is swimming round the top third of the tank!

Any ideas why he's doing this?

 

[Lauracooks]

I have one and apparently if they are not getting enough food from the sand they will go looking for pods elsewhere. thay can be jumpers too. do you have alge around intake? mine will go and (i think) eat the pods hanging out in hair alge.

 

[Triggerfish]

im not sure i have that many pods in my tank but my diamond goby sifts all day long. however it will occassionaly go mid level but not often.