The oblongums are juvies (2-3)" and the breeder said that they are super mellow, so I'm not too worried about the little keyhole.
I can't say how the keyholes and bolivians will do, as it's only been a day so far. Honestly, my keyholes like to hang out in the middle of the tank in the swords and driftwood, not on the bottom (except when they are sleeping). The bolivians have taken the front left where there is open substrate to sift... no surprise there, lol.