Also, remember that hillies need a mature tank to survive. They will not eat any prepared food. Generally, they survive off the biofilm (algae & other micro critters growing on surfaces in the tank.> You need to have that established before introducing the fish or they might starve to death.
White clouds are good companions to hillies, and you might also try weather loaches. At any rate, have the tank established for a few weeks (or months) with the other fish (wait till you have at least a light algae film) before introducing the hillies & you will have better success.
And a long tank is better for them, as you can create better currents. <OTOH, my hillies don't really seek out the current, staying mostly in the "shadows" of my water pump (it is 750 gph tho ....), so it may be the aeration & high O2 content, rather than current, that is absolutely necessary.>