H. salvini are a fairly aggressive and predatory cichlid.i kept one once with a 7 inch managuense if that tells you anything.
i second the above advice in that a 29 gallon is much to small to keep a fish that not only grows to a decent size but claims so much territory.
i have to be honest with you in that if you happen to get a more aggressive firemouth (as many do exist) he will likely remove all of your non-cichlid tankmates also.
while they grow slowly, they will reach 4-5 inches eventually--at which point i would keep an eye on even you apisto and krib in a 29 gallon.
i know it sounds like we are being harsh, but we donate much of our time trying to prevent people from making mistakes in this hobby--many of which lead to people giving up on it. (plus, many of these mistakes we have made ourselves
)
M