I use a very slow drip method.
Also I have 2 tanks waiting at a Ph of approx 6.8 I will introduce the fish to those tanks after the slow drip from pH 7.5 (Wet Spot keeps them at 7.5)
Then I slowly Lower the pH in each of the tanks with the Paros to get a pH of at least 5 if not lower.
My last order was for the Filamentosus and all 6 are well and in a pH of 5 for the time.
They seem to be quite adaptable as young fish, and as they mature, I will adjust for optimum breeding range water parameters. There is more than likely a broad range in their natural enviroment during rainy and dry seasons, that the Paros family has adapted to. Actually I was surprised at 100% survival from the dealers… Better than Apistos and other soft, acid water fish I have ordered in the past.
Just make slow changes and all should be ok!