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Best fish for a 300 litre tank

128 species on file have published minimum tank ≤ 300L (freshwater). 8 species need a larger minimum on file. This page filters — it does not replace the tank builder or pair checker.

A 300L is big-fish room. Adult oscars, jaguar cichlids, full clown loach groups, retail-sized common plecos, larger Central American cichlids, and proper African cichlid setups all work. The volume forgives serious feeding regimes and serious filtration loads. The forward length is enough to spread aggression across territory rather than across the glass.

Stocking philosophy

300L is for fish that need 300L. Stocking it with nano species wastes the room and the filter.

300L 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 (300L)·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.

Showing 40 of 47 — open species pages for the rest.

Specialist / high-load (even if min ≤ 300L)

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

Avoid at 300L (need larger min tank on file)

Stocking 300L with nano community fish is the classic 'I had volume' mistake. Six neon tetras and three corys in a 300L is a 60L plan in five times the water. The school still pins itself to a corner because the species cannot use the space, and the filter runs underloaded.

Published minimum volume greater than 300L — 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.

  • More water, more layout options

    With 300L you have room for two zones in the same tank. Adolfoi cory can take the open swim space and Bamboo Shrimp fills the planted side, but check the fin-nipper flags on both before stocking. Layout does not fix a nipper next to a long-finned target. 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, 128)

All freshwater species on file with min tank ≤ 300L.

Guides (same data model)

Other tank hubs

Categories in the suitable list