Slugs in my tank!

No clue about the slugs. For the aips, I'd suggest getting peppermint shrimp as I think they eat the anemones.
 
how many peppermint shrimp do i need for a 20l do u think i would need i do remember seeing one at the pet store for sale
 
Get at least 2 peppermints but make sure they are peppermints and not camelbacks. The camelbacks have a hump on their back, hence the name. Not all peppermints eat aptasia. It is a hit or miss thing. You could try squirting lemon juice in their mouth or buy Joe's Juice.
 
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