What's the minimum tank size for a blue acara, both volume and dimensions (if relevant)? Does the species variation matter ie. latifrons, pulcher, coeruleopunctatus, maracaibo etc.?
minimum is 29 gallons as they reach 8", i keep mine in a 55 with a salvini, convict, firemouth, bichir, pleco, etc. and its pretty peaceful for a cichlid.
I keep a pair in a 55 gal they are the only cichlids In The tank. I would not keep them in anything smaller then 55 gal. You could keep one in a 30 gal with no other cichlids. Some acaras are more aggressive then others they all have personality. My male is nice my female is a bully So it depends on the fish.