You can grow them from 2-3" up to about 8" in a 55g if you only have 1 or 2 cichla. After that you will want to step up in tank size considerably. It is best to grow them out in a small tank such as a 55g so that it is easier to feed them and get them to associate you with food. If you put them in too big a tank at too small a size, they may run and hide alot when you approach the tank making it a real nightmare to get them to ever eat anything other than live food. I kept 4 cichla in a 65g up untill they were about 7" or so. Now lets get into some particulars without writing a novel if that is possible.
Tank size: In the cichla world, width and length are better than height. The longer and wider a tank you can accomodate / afford, the better. Even full grown cichla will do fine with a tank 24"-30" tall. A 24" wide tank would be a minimum in most cases, but it is widely accepted that 36"-48" wide are more likely to be considered "lifetime" tanks. A good marker to consider when keeping these guys is the inches of fish per gallon rule. 10 gallons per inch of ADULT fish is a good start. For example if you have 40" of fish, then a 400g tank would be in order. If you start with three 3" cichla, they would be ok in 40g. As they grow in inches, so does the gallons required. As juvies the inches per gallon can be much less, in the range of 2-5g per inch. After the fish reach the 7-8" mark it should be considered time to move to the 10g per inch rule.
Filtration: Bio, Bio, Bio. These fish produce ALOT of waste. I would rival their waste output to large catfish. You really cant over filter the water with these guys. Overkill filtration is a good thing. Multiple stages of mechanical and tons of bio surface area are the key to keeping these guys happy and healthy. A stage of fairly porous mechanical like a sponge, then onto your bio media, then a second stage of finer mechanical will make the tank shine like a diamond. Large canister style filters and wet / dry sumps are commonly used.
Water Parameters:
Ph: In a perfect world, you would like to keep the Ph in your tank below the 7.0 mark for Cichla. 6.2 - 6.8 in most cases is considred to be ideal. But, Ph is not as critical as some other parameters. Cichla seem to display their best coloration in that range, but some of the most beautiful fish ive seen have been kept in Ph of 8.0 if not even slightly higher. When it comes to Ph, stability and consistancy is more important than the Ph itself.
Temp: 85-87 degrees. Period. These fish are fairly prone to disease and parasites, mostly so when juveniles. Maintaining a temp of atleast 87 degrees will ensure that most things such as Ich do not take hold and kill your Cichla. Another common practice is to use aquarium salt at all times. Follow the directions on the aquarium salt you buy for proper dosage. It is usually something like 1 TBSP to 5 gallons. Salt will not evaporate so do not add salt when topping off your tank, only to water that you take out or replace during setup / water changes. Also keep in mind that running your temps in the preffered range will cause dissolved oxygen to be very low. It is important to have good surface agitation or some form of heavy turbulance to keep good levels of oxygen infused in the water. Turbulance can also be obtained with use of an overflow or wet / dry sump.
Ammonia, nitrites, and nitrate: It is imperative to keep your ammonia and nitrites at absolute zero. The lower your Ph is, the less toxic ammonia in your tank will be, but cichla are not very tolerant of ammonia and exspecially nitrite no matter the Ph. This is why the use of heavy bio filtration is a must. Cichla seem to be very tolerant of high nitrates, but if you want to keep your fish looking and acting their best, keep your nitrates as low as you possibly can. This can only be acheived by regular water changes of 25-50%, usually performed weekly or bi-weekly.
Species: Begginers should probably stick to the more common and affordable species such as Monoculus or Occelaris. These are the species most commonly found in pet stores. Most species can grow to sizes of 24"+ over a lifetime. Most species tend to grow very quickly in their first year, up to 12"-14". After that, growth tends to slow considerably to the range of 1-4" per year. Another common species is the Temensis. This is a stunning species of cichla, but also one of the largest and fastest growing. It is not recommended to purchase a Temensis unless you have the capacity to maintain a tank in the range of 600 to 1000 gallons. There are many more exotic and expensive species available but a begginer should "crawl before you walk" so to speak.
Diet: As juveniles alot of cichla will only take live food such as guppies, goldfish, ghost shrimp, and other live types of food. If your fish will take prepared foods such as tiny pieces of raw shrimp, frozen bloodworms, pellets, and freeze dried krill at an early age you have a good head start on saving yourself alot of time and headache in the long run. There is risk when feeding live food of intoducing pathogens, disease, and parasites to your fish. But in alot of cases young fish will only take live food. If that is the case, then feed them all they will eat. It is commonly practiced to "quarantine" feeder fish in a seperate tank. Most keepers of young cichla will lamost always have a tank setup strictly for housing feeder fish. Keepers will buy a load of feeders and keep them in this tank for several days or even weeks, pulling out the obvious week or sickly ones as time progresses. This also allows you to "gut load" the feeders. This simply means giving them a heavy feed of highly nutritious food just before you net them out to feed to your cichla. This process ensures that your cichla are only getting the healthiest and highest quality feeders available. Avoid goldfish if at all possible. They have low nutritional value, but if that is all you have available they are better than nothing.
It is very important not to starve your young cichla just for the sake of getting them to eat prepared foods. When they are young they need lots of food to get their immune systems built and to gain strength. If they will take prepared foods early on that is fantastic. If not, then feed them whatever they will eat. As they get bigger towards the 6" mark you can start trying to force them onto prepared foods. This can be a long process but in time if you continue to offer the prepared foods they will eventually take a liking to them. Variety is a key to keeping your fish happy and healthy.
Hope this helps you out. There are some finer details that could be explained but I think this little overview should help you get started in the right direction. If you follw these steps, you should be on the right path to keeping one of the most Monster fish available in the hobby.
hes covered everything!