Tank size · Saltwater
What size tank for a Green chromis? (55 gal minimum)
Green chromis (Chromis viridis) — adult 3″, slim-bodied, schooling.
The three sizes — minimum, good, ideal
| Tier | Tank size | What it gets you |
|---|---|---|
| Absolute minimum | 55 US gal | Survives adult life. No extras — no tankmates beyond the essentials, no aquascape that eats footprint. |
| Good | 83 US gal | Room for a small community, decor, and parameter buffering. This is where most people should aim. |
| Ideal | 138 US gal | Natural-feeling space. Active swimmers stop pacing, schoolers school freely, aggression drops. |
Parameters at a glance
- Temperature
- 75–80 °F
- pH
- 8.1–8.4
- Salinity
- 33–35 ppt
- Adult size
- 3″
- Body type
- slim
Why tank size matters for this species
Green chromis is a schooling species — keep at least 5 together. The tank-size minimum above assumes that group. A single or pair-only setup stresses the fish, dulls colour, and shortens lifespan.
Common mistake
Expecting them to remain a peaceful school. They don't.
Source for the tank-size minimum
ORA care sheet.
Next steps
- ▸ Build a candidate stocking list with the aquarium stocking calculator — it'll warn if your community is incompatible.
- ▸ Confirm tank water volume after substrate and rock with the aquarium volume calculator.
- ▸ Read the nitrogen-cycle guide before adding the first fish.
People also ask
- What is the absolute minimum tank size for a Green chromis?
- 55 US gallons as an adult, no strict footprint requirement. ORA care sheet.
- Can I keep a Green chromis in a smaller tank when it's a juvenile?
- Briefly, yes — fish stores often sell juveniles that haven't reached adult size yet. But you should plan, buy, and cycle the adult-minimum tank from day one. Upgrading mid-life stresses the fish and is far more expensive than buying the right tank up front.
- Do Green chromis need to be in a group?
- Yes — they're schooling. A group of at least 5 together. Single or pair-only setups stress them, dull their colour, and shorten their lifespan. Plan tank size for the school, not the individual.
- What temperature and pH does a Green chromis need?
- Temperature 75–80 °F, pH 8.1–8.4, salinity 33–35 ppt.
- What's the most common mistake people make with Green chromis?
- Expecting them to remain a peaceful school. They don't.
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