FastAquatics
Tank stocking ideas

20-gallon tank stocking ideas

4 themed stocking plans with exact species + counts + notes. Pick the theme that fits your goals, then verify with the stocking calculator.

4 themed stocking ideas for 20-gallon

1. Community freshwater

  • 12x Cardinal tetras
  • 6x Corydoras (sterbai or panda)
  • 4x Otocinclus
  • 1x Pair German blue rams
  • 8-10x Amano shrimp

Notes: The all-time classic community. Schools up top, bottom dwellers + algae crew below, centerpiece pair in the middle.

2. Nano reef (20g long)

  • 1x Pair Ocellaris clownfish
  • 1x Yellow watchman goby + tiger pistol shrimp
  • 20x Mixed CUC (turbo, nassarius, hermits)
  • Soft coral + LPS frags

Notes: 30-inch footprint allows aquascape depth. AIO setups (IM Nuvo Fusion 20) are the easiest path.

3. Single-species cichlid

  • 6-8x Apistogramma cacatuoides (1M, 4-7F)
  • 8x Corydoras habrosus
  • 15x Cherry shrimp colony

Notes: Apisto harem with cory bottom-dweller. Highly territorial but interesting breeding behavior.

4. Heavily planted Iwagumi

  • 20x Chili rasbora school
  • 10x Otocinclus
  • 30x Cherry shrimp colony
  • Carpet (Monte Carlo or HC) + Iwagumi stones

Notes: Nature Aquarium style. High light + CO2 + EI fertilization. Highest visual impact for a nano.

Verify your stocking plan

Use the stocking calculator to verify the exact species + counts work in your 20-gallon. Also check the water change calculator for ongoing maintenance, and the setup guide library for the full build playbook.

Other tank sizes

Browse all stocking idea pages from 5g nano to 180g show-tier. Or jump to the stocking blueprints for build-along plans with timelines.