Aquarium stocking ideas by tank size

10 tank-size stocking guides. Each page lists multiple themed setups (community, reef, cichlid, planted, biotope) with exact species + counts + notes - skip the "what fish should I get" research and pick a proven plan.

5-gallon stocking ideas5g is the realistic minimum for ANY aquarium. Suitable for solo betta, shrimp colonies, or 1-2 micro fish. Below 5g is unfair to most species.4 themed setups 10-gallon stocking ideas10g is the most-flexible nano size. Supports community freshwater, planted nano, shrimp + dwarf fish, single betta with tankmates.4 themed setups 20-gallon stocking ideas20g (long preferred) opens up community + nano-reef + breeding setups. The 30-inch footprint of a 20g long is the sweet spot.4 themed setups 29-gallon stocking ideas29g is the sweet-spot community size. Standard 30"x12"x18" footprint allows schools + bottom dwellers + a centerpiece pair without crowding.4 themed setups 40-gallon stocking ideas40g breeder (36"x18") is widely considered the best mid-range tank. Wider footprint = better aquascape + nano reef + breeding.4 themed setups 55-gallon stocking ideas55g (48"x13"x21") is narrow but long. Best for community freshwater + smaller mbuna + larger schools. NOT ideal for reef due to narrow depth.4 themed setups 75-gallon stocking ideas75g (48"x18") is the sweet spot for serious reef + larger freshwater. The 18-inch depth front-to-back enables real aquascape + tang stocking.4 themed setups 90-gallon stocking ideas90g (48"x18"x24" or 36"x18"x30") is a step up from 75g - more vertical for aquascape, deeper sump options.4 themed setups 125-gallon stocking ideas125g (72"x18") opens up large oddball + tang school + premium reef builds. The 6-foot length is a major upgrade from 4-foot tanks.3 themed setups 180-gallon stocking ideas180g (72"x24") is show-tier reef + adult oddball. The 24-inch depth is finally enough for proper aquascape on a 6-foot tank.2 themed setups