Planning a community aquarium: which fish go together?

Temperature, water, swimming level and temperament: with these four questions you can plan a community aquarium where every fish feels at home. With examples for 60, 100 and 200 litres.

Boeseman’s rainbowfish, blue and orange, in a planted aquarium
Photo: FakirNL, CC BY-SA 4.0, via Wikimedia Commons

A community aquarium only really works when all inhabitants need the same conditions and leave each other alone. Ask yourself these four questions for every species.

1. Does the temperature match?

  • Cooler (18–24 °C): for example the white cloud mountain minnow (Tanichthys albonubes), many Corydoras species and the celestial pearl danio.
  • Medium (24–26 °C): most tetras, rasboras, livebearers and gouramis.
  • Warm (26–30 °C): cardinal tetras, rams and discus.

Choose species whose temperature ranges overlap.

2. Does the water match?

Livebearers and rainbowfish like medium-hard to hard water, many tetras and dwarf cichlids soft water. Tank-bred fish are often more flexible than wild-caught ones, but don’t combine the extremes. Test your tap water and choose species that suit it: that’s much easier than adjusting your water.

3. Which swimming level?

An aquarium looks more lively when every water layer is inhabited:

  • Top: hatchetfish, gouramis, some livebearers.
  • Middle: tetras, rasboras, barbs, rainbowfish.
  • Bottom: Corydoras, loaches, Ancistrus.

4. Does the temperament match?

  • Fin nippers such as the tiger barb don’t belong with long-finned fish such as bettas, guppies or angelfish.
  • Big fish eat small ones: an adult angelfish eats neon tetras.
  • Territorial fish, such as some cichlids, need space and hiding places.
  • Schooling fish are only at ease in a group: at least eight to ten of the same species.

Example stocking lists

60 litres

  • 12 chili rasboras or 10 celestial pearl danios
  • 6 dwarf Corydoras (Corydoras pygmaeus or C. hastatus)
  • Shrimp (Neocaridina) and snails

100 litres

  • 12 neon or cardinal tetras
  • 8 harlequin rasboras
  • 1 dwarf gourami or honey gourami
  • 6 Corydoras

200 litres

  • 8 Boeseman’s rainbowfish
  • 15 cardinal tetras
  • 1 pair of pearl gouramis
  • 8 Corydoras and 1 Ancistrus

Adding fish

  1. Let the aquarium fully cycle first (see our article on the nitrogen cycle).
  2. Start with the hardiest species, in small groups.
  3. Then add the next group every few weeks, so the filter can grow along.
  4. Add the most territorial fish last.