Info of my tank

[halpmeplz]

I have a 20 gallon tank with 5 mollies and 3 skirt tetras, and one mystery fish. I use disstiled water from the store. I am also in the middle of an invasive of bladder snails.[emoji22] i think they came when I bought my plants.

 

[ZxC]

I would be cautious of using distilled water, that's asking for a pH crash. What is the ph of the tank? Anything in the tank that will buffer against a pH change?
Any photos of the mystery fish?
Limited feedings and manual removal is the only way you will get rid of the snails. I'm not convinced you are using distilled water only.... the snails wouldn't last long without minerals in the water.