Hello All!

I have an African clawed frog and he is just as happy as can be in his tank, but when I put him into a smaller one to clean his, he's not the happiest so he made an escape from his "holding" tank. It scared me half to death so for the last couple of nights I'm worried about him escaping his normal tank since he's starting to get curious! The top of the tank's lid was designed to where it is like open in a corner to feed the filter cords and such. I've had a piece of paper covering it till I got my new filter today. But the filter is a long filter and he can easily climb up the thing and out! So can someone recommend how to cover this area so he doesn't get out! Pictures would be helpful too because I tried asking friends about it and totally got confused!

All help is appreciated! Thank you!