Frontosa's are perhaps semi-aggressive in temperment (although mature male vs mature male aggression can be of greater intensity). They're generally slow swimming fish though can be timid or skittish at times.
Best kept with other frontosas and in my experience tend to do best in colonies of at least six or more. They can get fairly large, as previously stated, males can easily attain and even exceed a foot in length, aquariums 6ft or more in length are best for them. May eat smaller fish if they happen to be housed with them (they're nocturnal piscovores by nature).
Here are some of the frontosa variants I have:
Burundi (they tend to develop the largest nuchal humps):
Kigoma (the 7-stripe variant, I've found them to be the shy-est)
Mpimbwe (very outgoing)
Kipili (a Tanzanian similar to the Mpimbwe)
Kapampa/Zaire Blue