It's very likely that the kribs and blue acaras will not be able to co-exist peacefully in the 29 in the long-run. The blue acaras, depending on species, can reach 8" and should be housed in a bigger tank anyway. A spawning pair of kribs will take up much of the footprint of the tank for themselves.
If you chose kribs for the tank you could keep other fish but would be restricted to dither-type tankmates such as barbs, tetras, livebearers or rasboras.