A community tank is multiple species coexisting peacefully. Done right, beautiful and engaging.

Tank size for a community

  • 20 gallons: minimum.
  • 30+ gallons: easier, more options.
  • 55+ gallons: ideal for variety.

The four "zones"

  • Top swimmers: hatchetfish.
  • Mid-water: tetras, rasboras, gouramis.
  • Bottom dwellers: corydoras, loaches, plecos.
  • Plant area: shrimp, smaller schooling fish.

Balanced community has fish across these zones.

Schooling fish: minimum group sizes

Most schooling fish need groups of 6+ to feel safe and behave naturally. Below 6 are stressed.

Recommended combinations

Small community (20 gallons):

  • 6× Neon tetras (mid)
  • 6× Cherry shrimp (plant)
  • 6× Pygmy corydoras (bottom)
  • 1× male Betta

Standard community (30 gallons):

  • 8× Cardinal tetras
  • 6× Harlequin rasboras
  • 6× Corydoras
  • 1 pair Honey gouramis
  • 4× Otocinclus

Larger (55 gallons):

  • 10× Cardinal tetras
  • 8× Harlequin rasboras
  • 1 pair Pearl gouramis
  • 6× Sterbai corydoras
  • 1× Bristlenose pleco
  • 2× Apistogramma cichlids

Compatibility rules

  • Peaceful + peaceful: generally compatible.
  • Aggressive + peaceful: usually fails.
  • Schooling + lone fish: works well.

Species to avoid in community tanks

  • Tiger barbs (in groups under 8): nip fins.
  • Most cichlids: aggressive territorial.
  • Goldfish: different temperature; outgrow tanks.
  • Oscars: get huge.
  • Common plecos: grow to 2 feet.

Specific compatibility

Bettas: One male per tank with calmer fish. NO multiple males. NO long-finned slow tankmates.

Gouramis: Pairs work. Two males of same species fight.

Plecos: Bristlenose stays small. Common pleco grows huge.

Corydoras: Universally peaceful. Need bottom space.

Water parameters

  • Temperature: 76–80°F.
  • pH: 6.5–7.5.
  • Hardness: 5–15 dGH.

Aquarium plants

Plants enhance: provide cover, absorb nitrates, grazing surfaces, aesthetics.

Easy plants: Java fern, Anubias, Water sprite, Java moss, Vallisneria.

Stocking strategy

  1. Cycle tank (4–6 weeks).
  2. Add bottom-dwellers first. Wait 2 weeks.
  3. Add main schooling species. Wait 2 weeks.
  4. Add second schooling species. Wait 2 weeks.
  5. Add showpiece fish last.

Algae and cleanup crew

  • Otocinclus: peaceful in groups.
  • Bristlenose pleco: larger algae eater.
  • Cherry shrimp: detritus and algae.
  • Amano shrimp: very effective.

Don't over-rely on algae eaters. Manual cleaning + reduced lighting is more effective.

Calculate tank

Our fish tank volume calculator handles dimensions to gallons.