Ocellaris Clownfish

Overview

• The Ocellaris is the orange-and-white clownfish often called "Nemo" and is a good marine fish for beginners.
• Most stock sold today is captive-bred, which makes it hardy, adaptable to aquarium foods, and less prone to disease than wild-caught fish.
• It is also among the milder-tempered clownfish.

• It does not need a host anemone to thrive, which is helpful because anemones are demanding and better suited to experienced keepers.
• A single fish or a bonded pair works well.
• Its bold, personable behaviour makes it a watchable centrepiece.

Housing

• A cycled tank of 75L (20 gal) or more suits a pair, with live rock for territory and a tight-fitting lid since clownfish can jump.
• Maintain salinity 1.024-1.026, temperature 24-27°C (75-80°F), pH 8.1-8.4, with ammonia and nitrite at zero and nitrate below 20 ppm.

• Add fish only to a fully nitrogen-cycled system; new tanks need several weeks to establish beneficial bacteria.
• Stable parameters matter more than perfect ones, so use a reliable heater, a powerhead for flow, and a quality test kit.

Diet

• Ocellaris are omnivores.
• Offer a quality marine pellet or flake as a staple, supplemented with frozen mysis and brine shrimp and occasional algae-based foods.
• Feed small amounts once or twice daily, only what the fish finish in a couple of minutes, to keep nitrate low.

• Captive-bred fish accept prepared foods readily, so weaning is rarely an issue.
• Vary the diet for colour and immune health, and soak frozen foods in a vitamin supplement now and then.
• Avoid overfeeding, the most common cause of poor water quality.

Health

• Clownfish are robust but susceptible to marine ich (Cryptocaryon) and the clownfish-specific Brooklynella if stressed or kept in poor water.
• Quarantining new arrivals and maintaining stable salinity and temperature prevent most outbreaks.

• Watch for rapid breathing, scratching against rock, or white spots, which signal parasites.
• Good filtration, regular water changes, and a varied diet support the immune system.
• Captive-bred stock generally ships healthier than wild-caught fish.

Temperament

• Ocellaris are peaceful by clownfish standards and reef-safe, generally ignoring corals and most tankmates.
• A bonded pair forms a hierarchy, with the larger fish becoming female; all clownfish begin as males and the dominant one changes sex.

• They can be mildly territorial around their chosen spot but rarely cause real trouble.
• Keep only one fish or one bonded pair, since two unbonded clownfish, especially of different species, often fight.
• They make confident, interactive display fish.

Is your enclosure big enough?

Check your own enclosure against this

Is this urgent?

In a reef, stability matters more than any single target number. A parameter moving fast does more damage than a parameter sitting slightly off.

Go now

Today

Quarantine every new animal, including corals and inverts. It is the single practice that separates a reef that lasts from a reef that restarts.

This is general guidance for a healthy adult, not a diagnosis. An exotics vet who knows your animal always overrides it — and the time to find one is before you need one.

What it really costs

Setup, monthly, first year and across a whole life, itemised and with the electricity worked out from the actual wattage. Published figures for the same animal disagree by a factor of four, so the calculator shows ranges rather than picking one.

Work out the cost of a ocellaris clownfish