Finally added fish to the new tank, now a have a new issue

[fishyG]

So I added the fish after having the tank running for a while with just the LR. Everything is going fine until one of the new fish goes missing. It is a little yellow Clown Goby. I finally find him in the over flow swimming around the pre filter. He got into the overflow in the tank and must have been sucked to the outside box.
Well I know he likes to sit on the PH right near the overflow, so I moved that. Well the next day he was in there again. And this morning too. He seems fine, and he can get food in there. But still, I don't want him in the over flow. I have thought of adding another pre filter to the bottom of the tube from tank side to outside, and I have thought of a net or prefilter in the slits at the top of the overflow. But both of those will stop any floating objects there, and I am worried that he will swim up there more to check that out. Plus, if it is a case of him getting sucked in, then couldn't that just pin him there?
Any help or ideas would be great. I really like that little guy and want to get one more, but not if they are going to live inthe over folw

G

 

[lando]

Any way you can lower the water level a bit? He may not be able to make it in there then.
BTW...where are you at in MN? I live in Savage.

 

[runway1]

I bought a small, $3 fish net. I tore off the netting and draped it around the slots in the overflow box. This kept me from findin my fish in it.