Forget about it. A single venustus will outgrow a 29 gallon tank in a few months (assuming it was about 2inches at purchase). They reach 10 inches at maturityand need to be ina 5-6ft tank. 29 is really too small for any Malawi species long term. You could possibly do a small group of Ps. saulsoi or a small demasoni colony (12-14 fish), but thats about it.
yeah... they get a foot long so nope. try getting dwarf ramirez's (south american's) common name Ram's, blue, german, bolivian, etc. they are just pretty as can be and stay relatively small. also there are some other dwarf south americans that i cant remember.. just look em up they are from the mexican peninsula and are just pretty as can be. just try and stay with smaller fish and maybe some schools of tetras or something so that your tank looks full. anyways good luck