FastAquatics
Tank stocking ideas

40-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 40-gallon

1. Mixed reef (40g breeder)

  • 1x Pair Ocellaris clownfish
  • 1x Royal gramma
  • 1x Yellow watchman goby + pistol shrimp
  • 1x Six-line wrasse (LAST)
  • 20+ CUC
  • Soft + LPS coral collection

Notes: The 36"x18" footprint allows real aquascape with multiple coral zones. Best entry-level reef size.

2. Discus pair

  • 1x Pair Discus (or 6-8 juveniles)
  • 8x Cardinal tetras (provide them company)
  • 4x Bristlenose pleco
  • Driftwood + smooth river stones

Notes: Discus-only setup with tetra dither fish. RODI + soft acidic water. Daily feeding = active growth.

3. Heavily planted aquascape

  • 25x Cardinal tetras
  • 8x Corydoras
  • 6x Otocinclus
  • 1x German blue ram pair
  • 15x Amano shrimp
  • Iwagumi or Nature Aquarium style

Notes: High-tech planted with CO2 + EI fertilization. Carpet plants + stems + epiphytes.

4. Apistogramma harem

  • 1x Apistogramma cacatuoides male
  • 4x Apistogramma cacatuoides females
  • 12x Ember tetras (dither)
  • 6x Corydoras habrosus

Notes: Multiple territories form. Breeding triggered by water changes + temperature drop.

Verify your stocking plan

Use the stocking calculator to verify the exact species + counts work in your 40-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.