Need Ideas for keeping Fish out of Overflow

I made a DIY internal overflow box from glass and acrylic for my 46 bowfront. I have had 1 of my clowns in the box twice having to remove it by hand and twice it has made it all the way down the plumbing ending up in the sump.

I'm trying to come up with ideas on how to keep them out of the overflow.

Here is what it looks like. I have a glass versa top on the tank so there is only 1/2 to 3/4 inch between the top of the overflow and the bottom of the lid. I thought about putting sponge all the way around on the rim of the overflow but didn't know if that would hurt the surface skimming performance.

 

make it come up higher from the surface or cover it

 

I've never had one in mine.. How about a tank divider? mesh type.

 

Plastic gutter guard works really well.

 

+1 on gutter guard

 

Can you get gutter guard at home depot or lowes?

 

Eggcrate (light diffuser) is what I use.

 

sponge - that's what I put in mine

 

yeah I have a big sponge over my overflows....works well. I have not had any fish in there since and it also helps block out the light to that so the algea problem is gone in that area.

 

+2 on gutter guard, you can get it at Lowe's, HD, Ace, Menards...... Reason I use it is it doesn't slow the flow down one bit and it can be form fitted to almost any shape and size with a pair of household scissors.