Covering tank and filter for Kuhlis?

[Jenna]

Hi, I've read Kuhlis will squeeze in to any tiny space and filter and aquariums need to be covered... I'm attaching pics of the top of my aquarium that is left open and my filter.
The filter - does it need to be covered with these slots? There's carbon foam right behind... is that something they can wriggle in to?! And if so, what is recommend to cover it?
The aquarium lid - what can I use to cover this small space? I used duct tape (gaffa tape) when I had fiddler crabs before, but I'm not sure that would be appropriate for the fish.

Thank you!

[TropicalFishForums]

[Jenna]

Other pic.

[plankton]

A strip of spong along the top and down the sides of the filter should stop them.
As they get fatter you can remove it from around the filter.

[Jenna]

Oh! So it's more AROUND the filter that's the issue rather than them getting actually IN to it? Okay, I can handle that. Thank you!

[plankton]

They've been known to get in externals, they get through the mesh/grille for input (to the filter), but I've not known it with internals.