Best Fish for a 100 Litre Tank UK

Quick answer — 5 proven 100 L community examples

Community A — "Classic peaceful community"

• 1 × Honey gourami pair (centrepiece)
• 12 × Cardinal tetras (mid water)
• 8 × Corydoras sterbai (bottom)
• 1 × Bristlenose pleco
• 8 × Amano shrimp

Community B — "Dwarf cichlid biotope"

• 1 pair × German blue rams (centrepiece)
• 12 × Cardinal tetras (mid water dither)
• 8 × Pygmy corydoras (bottom)
• 1 × Bristlenose pleco

Community C — "Schooling spectacle"

• 15 × Cardinal tetras
• 12 × Harlequin rasboras
• 8 × Corydoras
• 8 × Amano shrimp

Community D — "Livebearer paradise"

• 8 × Platies (mixed colours)
• 8 × Endlers (males only)
• 6 × Corydoras
• 1 × Bristlenose pleco

Community E — "Asian biotope"

• 1 × Sparkling gourami pair (centrepiece)
• 12 × Harlequin rasboras
• 8 × Kuhli loaches (bottom)
• 8 × Amano shrimp

Why 100 L is a great size

100 L is the size where most beginner mistakes get forgiven. More water = more stable temperature, more stable parameters, more buffer against ammonia spikes. You can:

• Keep proper dwarf cichlid pairs
• Run a school of 12+ tetras (real visual impact)
• Add a clean-up crew without overcrowding
• Forgive minor overfeeding without losing fish

It's the sweet spot for new keepers who want a proper community without the cost of a 200 L+ setup.

Best species for 100 L by role

Centrepiece options (1 fish or 1 pair)

• Honey gourami — peaceful, smaller than dwarf gourami, better community fit
• Pearl gourami — bigger but stunning, peaceful
• German blue ram (pair) — colourful but needs warm 27-29 °C
• Apistogramma (pair) — many species, all peaceful but territorial during breeding
• Bolivian ram (pair) — easier than German blue, tolerates 24-26 °C
• Single angelfish (1 only — they fight in pairs unless 200 L+)
• Kribensis (pair) — beautiful when breeding, some aggression to others

Schooling species (groups of 8-12)

• Cardinal tetra, neon tetra, ember tetra, black phantom tetra
• Harlequin rasbora, lambchop rasbora, espei rasbora
• Cherry barb, gold barb (peaceful barbs)
• Zebra danio, leopard danio
• Diamond tetra (slightly bigger, 5 cm)

Bottom dwellers (groups of 6-8)

• Corydoras (any species — sterbai, panda, paleatus, julii, bronze)
• Pygmy corydoras (group of 8-10 — smaller, very active)
• Kuhli loach (group of 6 in sand substrate)
• Bristlenose pleco (1 only)

Inverts

• Amano shrimp (5-10) — best algae cleaners
• Cherry shrimp (10-20) — colourful + breeds
• Nerite snail (3-5)
• Ramshorn / mystery snails (1-2)

Equipment for 100 L tropical tank

Plus £60-150 for fish/shrimp.

Common 100 L mistakes

Mistake 1: "I'll add a pair of angelfish + a pair of discus + tetras"

Why it fails: Angelfish + discus is high-tension at the best of times. 100 L is too small for either pair to thrive properly.

Fix: Pick ONE centrepiece species per tank. If you really want angelfish, go up to 200 L. For discus, 250 L+.

Mistake 2: "More fish = more fun"

Why it fails: Overstocking causes ammonia spikes, fights, disease. A 100 L stocked with 60 fish is worse than one with 30.

Fix: Stay at 25-35 small fish total. Quality > quantity.

Mistake 3: Two dwarf cichlid species in same tank

Why it fails: Apistogramma + ram + kribensis all want similar territory. Constant fighting, especially during breeding.

Fix: ONE cichlid pair per tank. Multiple cichlid species need 250 L+ with rockwork divisions.

Mistake 4: Skimping on filtration

Why it fails: A small 100 L filter on a stocked 100 L tank can't keep up. Ammonia + nitrite spikes.

Fix: Buy a filter rated for 150-200 L. Oversized filtration is forgiving filtration.

Summary

100 L is genuinely versatile. Pick one centrepiece, one schooling group, one bottom group, plus inverts. Don't overstock. Don't mix incompatible species. The result: a thriving tank that needs minimal drama for years.

Related guides

• Best Fish for a 30 Litre Tank
• Best Fish for a 60 Litre Tank
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• Tropical Fish Tank Temperature
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