REALLY IMPORTANT HELP NEEDED--Beani, Cichlasoma

[Reptic Fish]

My LFS is getting some Cichlasoma Beani's! I have a 29 gallon tank. The beani's they are getting are small, 3 inches.
I was wondering how long can I keep a beani in 29 until I need to upgrade? He/She will solo.
How do I keep the beani alive? How often do I need to feed and change the water? I want to keep it away from bloat.
They look like this..

 

[AQUAMONSTER]

looks like a beani. From what ive gathered in my research before i get mine is this. Try keeping them alone or remove them if aggression is high. Feed evry other day and remove all uneaten food and do 25-50% water changes a week.Since water quality is the most important thing for this fish but it is for all i will be keeping mine with a sand bottom to avoid all the waste from using gravel. Since switching to sand i feel my fish are must happier and healthier. Over filtrate with this fish even with the 29 i would throw a emp400 on it. I would also use a very dim light since they can be very skiddish when small. I have grammodes right now which are prone to bloat and i only feed 1-2 times every other day and they have a dim light and are doing very well and its what ill do when i get my beanis.... Good luck