Short answer
Captive-bred ocellaris clownfish pair, royal gramma, firefish, banggai cardinalfish, six-line wrasse, yellow watchman goby, tail-spot blenny, neon goby, and a small selection of corals. Avoid tangs, large angels, and most aggressive species in this footprint.
In depth
A 30-gallon saltwater tank is the smallest size that supports a meaningful reef community without compromising fish welfare. The footprint (30"x12"x18" typical) gives enough territory for 3-5 small fish + a clownfish pair + cleanup crew + corals.
Stocking plan for a 30-gallon mixed reef
- Pair of captive-bred ocellaris - the centerpiece
- 1 royal gramma OR 1 firefish - vivid color, peaceful, occupies a different swimming zone than clownfish
- 1 small goby - yellow watchman, neon, or a small clown goby
- 1 small blenny (optional) - tail-spot or canary blenny
- Cleanup crew - 15-20 snails (mix of turbo, trochus, cerith, nassarius), 5-7 hermit crabs, 1-2 cleaner shrimp
- Corals - 5-15 specimens depending on growth speed and tank maturity
Avoid in 30 gallons
- Tangs (need 75-125+ gallons)
- Large angels (queen, emperor, French - 180+ gallons)
- Triggers (75+ gallons)
- Wild-caught clownfish (parasites + disease risk)
- Mandarins, dragonets (specialized live copepod diet)
- Two species of clownfish (will fight)
More questions
Can I keep a tang in a 30-gallon?
No. Even the smallest hobby tangs (kole, tomini) need 75 gallons minimum. Stunting a tang in an undersized tank causes premature death.
How many corals can I fit in a 30-gallon?
15-25 specimens depending on growth speed. Mostly soft coral and LPS for a beginner; one or two hardy SPS (montipora) for the second year.