the leaves are mostly used for my Bettas...
the leaves are a natural water conditioner. they leech tannin into the water but also have some anti-bacterial/ anti-septic properties from what I've heard...
They're not that big a deal and wont really be of use in your tank because your pleco would likely just eat them LOL
If you want to research them they're called Indian Almond Leaves.
You have to order them from Thailand(in most cases).