Just be careful to acclimate them slowly if they are not already in water like yours.
pH swings are much more harmful than a steady pH that is out of the normal range for the fish. I would not mess with chemicals to lower it.
You can add a nice big piece of driftwood, almond leaves or put some peat under your gravel or in a bag in your filter. These will SLOWLY and regularly leach natural organic acids into the tank that will lower your pH without the rapid changes that can be caused by adding chemicals that dissolve almost instantly. It isn't necessary, but if you wanted to match their naturally occurring habitat, that's the way I would do it. Just be aware, all of these will stain your water a gold-ish color.