Usually tank bred fish can adjust to different pH level as long as they are stable. In a 3 1/2 foot tank you should be able to do a pair of each, an maybe more depending on if they are a mating pair. They will not disrupt the plants and as long and there is a lot of hiding places, and ornaments for sightline break ups then you should be just fine. They are mostly bottom dwellers so you can get all sorts of tankmates from tetras and rasboras, catfish, loaches, gourami, and even other smaller less agressive cichlids like angel, festivum, keyhole, rainbows. 10 penguin tetras, 1 albino BN Pleco, 2 apistos, 2 blue rams, 2 festivum, and 2 keyholes would be a nice start.