How to stop Kuhli Loaches from going into overflow?

[white specter crayfish]

My tank has an overflow which I have covered with filter sponge and a screen, but my kuhli loaches still get in there and die, is there anything else I can do to stop this, I'm getting ready to just glue/silicone it off because I can't keep losing them like this. My dad said to move the 10 kuhli loaches into my 10 gallon tank with pea puffers, a killifish, bumblebee gobies, and a julidochromis dickfeldi but the loaches would get picked on to no end and the stocking would be too much, so I really have no choice as to what to do

 

[BichirKing]

got a pic of the over flow?

 

[white specter crayfish]

got a pic of the over flow?

got a pic of the over flow?

I think they’re getting In through the sump thats meant for the heater/protein skimmer, I’ve filled the compartment with sponges and have a screen over it but they still somehow get in, anyways here’s a pic of the overflow

 

[BichirKing]

I've used this plastic mesh and some zip ties to make a cover for my overflows before to keep my eels from getting in. you can pick it up at Walmart in the craft section. its used for cross stitching. completely inert so it wont affect your water or animals.

 

[white specter crayfish]

I've used this plastic mesh and some zip ties to make a cover for my overflows before to keep my eels from getting in. you can pick it up at Walmart in the craft section. its used for cross stitching. completely inert so it wont affect your water or animals.

I've used that too, doesn't work, they find a way around it

 

[celebrist]

I just let my khulis live in the sump. They even bred in there

 

[white specter crayfish]

I just let my khulis live in the sump. They even bred in there

no when they go in there they die, idk why tho, plus I never see them