I am setting up a 55 gallon tank and wanted to know what is the proper amount of Malawi cichlids to add. I have a canister filter in combination with a pentair fluidized bed filter. I am currently cycling the tank with goldfish to get it established. I have good substrate and lace rock to help buffer the high ph cichlids need. Are there any Malawi's that I shouldn't mix? Should I purchase them all at once and add to the tank or a few at a time? And what other than cichlids go well with the water quality (plecos/catfish)? I have had simple tetras but this is my first "real" tank. Any suggestions from you experts would be greatly appreciated.