Last updated: Jul 15, 2026 ยท Last checked: Jul 15, 2026
Best Fish for 20 Gallon Tanks
This is where beginner-friendly community tanks start getting much more flexible. You get room for a centerpiece species, fuller schools, and more balanced layouts.
Top picks
1. Honey Gourami (Trichogaster chuna)
Best for: peaceful centerpiece community
Why it makes the list: calm, colorful, and one of the best centerpiece fish for smaller communities.
- Adult size: about 2 inches
- Behavior: peaceful labyrinth fish, usually one male works best
- Water: 74 to 82 F, pH 6.0 to 7.5
- Diet: quality pellets plus frozen foods
- Setup: floating cover and gentle flow
- Watch-outs: boisterous tankmates suppress feeding
- Buying note: prioritize healthy, well-conditioned stock
2. Harlequin Rasbora (Trigonostigma heteromorpha)
Best for: classic community midwater school
Why it makes the list: reliable, attractive, and easy to build a community around.
- Adult size: 1.5 to 2 inches
- Behavior: schooling fish
- Water: 73 to 80 F, pH 6.0 to 7.5
- Diet: small pellets, flakes, frozen foods
- Setup: open swim lane with surrounding plant cover
- Watch-outs: tiny groups raise stress
- Buying note: avoid mixed leftover batches
3. Panda Corydoras (Corydoras panda)
Best for: active bottom group in cooler tropical tanks
Why it makes the list: one of the best-looking small corys for planted community tanks.
- Adult size: around 2 inches
- Behavior: social bottom schooler
- Water: 72 to 77 F, pH 6.0 to 7.5
- Diet: sinking foods and frozen treats
- Setup: soft substrate and shaded rest zones
- Watch-outs: warm, low-oxygen water reduces resilience
- Buying note: acclimate slowly after arrival
4. Apistogramma borellii (Apistogramma borellii)
Best for: pair-focused, more advanced community
Why it makes the list: one of the better dwarf cichlid options for a 20 gallon footprint.
- Adult size: 2.5 to 3 inches
- Behavior: territorial, especially when breeding
- Water: 72 to 79 F, pH 6.0 to 7.5
- Diet: protein-rich small pellets and frozen foods
- Setup: caves, leaf litter, line-of-sight breaks
- Watch-outs: cramped hardscape leads to aggression
- Buying note: verify sexing before purchase