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Best Nano Reef Fish for UK Tanks

reefsy

reefsy

March 1, 2026

Small Tanks, Big Decisions

Nano reefs are massive in the UK. A well-stocked 60-litre cube can be just as impressive as a 500-litre system. The challenge is stocking — some fish that thrive in large tanks will suffer in a nano.

Top Tier (60 Litres and Up)

Pair of Captive-Bred Clownfish — Perfectly happy in 60 litres. Low bioload, easy to feed, endlessly entertaining.

Tailspot Blenny — Genuinely perfect for nanos. Tiny, packed with personality, eats algae. One per tank.

Clown Goby — 3cm max. Sits in SPS branches. Yellow and green varieties most common. Peaceful and reef-safe.

Neon Goby — Electric blue stripe, cleaner fish behaviour, and increasingly available as captive-bred.

Second Tier (80–120 Litres)

Yellow Watchman Goby — Gets about 10cm. Pairs well with a pistol shrimp. Needs a decent sandbed (5cm+).

Royal Gramma — 80 litres minimum. Claims a cave and patrols a small territory. Colourful and hardy.

Firefish — Hovers in the water column, making smaller tanks feel spacious. Jumpers, so a lid is essential.

Possum Wrasse — Stays under 8cm. Secretive but beautifully coloured. One of the few wrasses that work under 100 litres.

Fish to Avoid in Nano Tanks

  • Any tang — need swimming space nanos can't provide
  • Larger wrasses — fairy and flasher wrasses need 150+ litres
  • Most dottybacks — too aggressive for small tanks
  • Six line wrasse — can bully with nowhere for tankmates to hide
  • Mandarin dragonet — insufficient copepod supply in nanos

Stocking Density

For 60 litres: two to three small fish maximum. A pair of clownfish and a blenny is ideal. For 100–120 litres: three to five small fish. Always check the adult size, not the juvenile size in a listing photo.

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