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Best fish for a 100 litre tank

86 species on file have published minimum tank ≤ 100L (freshwater). 50 species need a larger minimum on file. This page filters — it does not replace the tank builder or pair checker.

A 100L is the standard community tank in most starter kits. Two schools plus a pair of dwarf cichlids plus an algae crew works honestly here, as long as the schools are nano-class under 5 cm and the cichlid is genuinely dwarf. The volume forgives missed water changes for longer and lets a heater dial misfire by a degree without crashing fish.

Stocking philosophy

100L is the first tank that holds three species without trade-offs. The trade-off comes back the moment you add a fourth.

100L mistakeBuying the fish at the length you see in the shop, not the adult length on its profile. The shop length is six months old at most.

Open tank builder (100L)·Pair checker·All fish

Good first pass (conservative community rules)

Beginner/intermediate peaceful, not predatory, not a small-tank fin-nipper below 80L — adult size capped for very small hubs. Still read each profile.

Beginner-peaceful picks (subset)

Care beginner, peaceful, not fin-nipper, not predatory — same filter as before, stricter care label.

Caution (suitable by min tank, not a free “community” pass)

Fin nippers, semi-aggressive, advanced care, large groups, or may-eat-small-fish on file — may work in a mature, species-appropriate setup.

Specialist / high-load (even if min ≤ 100L)

Predatory, aggressive, advanced, large group needs, or may-eat-small — not typical community-first stocking.

Avoid at 100L (need larger min tank on file)

Adult angelfish need more height than most 100L tanks give. Common plecos and clown loaches still outgrow this volume long-term. Two-foot rainbowfish are a 250L decision, not a 100L compromise. Adult denisons barbs and bigger gouramis push the upper edge.

Published minimum volume greater than 100L — do not plan these for this class of aquarium.

Example sketches (illustration only)

Not a stocking guarantee — every mix needs the builder and pair checks.

  • Beginner community sketch

    Example mix to research: Amano Shrimp with Beckford Pencilfish, Black Neon Tetra, Black phantom tetra. Each pairing still needs the pair checker. The substrate and heater matter more than people give them credit for, so pick those once and well. Run it through the tank builder before you buy. The size and colour of fish in a shop tank are not stocking proof.

  • Planted peaceful lean

    More footprint than a strip tank: Adolfoi cory alongside Bamboo Shrimp, with plants tall enough to break the sight line between the two species. Flow rate and group sizes still come from the species pages, not from a sketch on this page. Run it through the tank builder before you buy. The size and colour of fish in a shop tank are not stocking proof.

Common mistakes at this volume

  • Buying the fish at the length you see in the shop, not the adult length on its profile. The shop length is six months old at most.
  • Under-schooling tetras, rasboras, or barbs. The fish look sick during the first week, and the diagnosis is almost always group size, not disease.
  • Mixing fin-nippers with slow or long-finned fish without checking the fin-nipper flags. Most personality clashes you read about online are layout problems with a named scapegoat.

Suitable for this volume (full list, 86)

All freshwater species on file with min tank ≤ 100L.

Guides (same data model)

Other tank hubs

Categories in the suitable list