What is the absolute minimum tank size for a Ocellaris clownfish?

20 US gallons as an adult, no strict footprint requirement. ORA / Sustainable Aquatics husbandry guides.

Can I keep a Ocellaris clownfish 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.

Can I keep more than one Ocellaris clownfish together?

It depends on the species' behaviour (semi-aggressive). Aggressive and semi-aggressive species often need to be kept solo unless the tank is dramatically larger than the minimum. Verify before adding a second.

What temperature and pH does a Ocellaris clownfish need?

Temperature 76–80 °F, pH 8.1–8.4, salinity 33–35 ppt.

Tank size · Saltwater

What size tank for a Ocellaris clownfish? (20 gal minimum)

Ocellaris clownfish (Amphiprion ocellaris) — adult 3″, medium-bodied, semi-aggressive.

The three sizes — minimum, good, ideal

Tier	Tank size	What it gets you
Absolute minimum	20 US gal	Survives adult life. No extras — no tankmates beyond the essentials, no aquascape that eats footprint.
Good	30 US gal	Room for a small community, decor, and parameter buffering. This is where most people should aim.
Ideal	50 US gal	Natural-feeling space. Active swimmers stop pacing, schoolers school freely, aggression drops.

Parameters at a glance

Temperature: 76–80 °F
pH: 8.1–8.4
Salinity: 33–35 ppt
Adult size: 3″
Body type: medium

Source for the tank-size minimum

ORA / Sustainable Aquatics husbandry guides.

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.