Nano Cichlids (under 100L)
Shell dwellers (multies, similis): 40L for 6-8. Apistogramma pair: 60L. German blue ram: 80L pair.
Keep water chemistry stable with small water changes twice weekly.
Medium Cichlids (100-400L)
Convicts pair: 150L. Firemouth pair: 200L. Severum pair: 250L. Angelfish group: 300L.
Mbuna colony (15 fish): 300-400L with heavy filtration.
Large Cichlids (400-900L)
Oscar pair: 500L+. Jack Dempsey pair: 400L. Flowerhorn solo: 400L (500L+ for 40cm+ specimens). Frontosa colony: 500L+.
These need sumps or dual canisters for filtration.
XL Cichlids (900L+)
Oscar trio: 900L+. Large haps (Nimbochromis, Aulonocara groups): 700L+. Wolf cichlid, dovii: 1200L+ minimum.
At this scale, custom tanks are often needed. Building materials become industrial.