Ocellaris Clownfish
Amphiprion ocellaris
Hardy, beginner-friendly reef-tank clownfishBeginner
- Lifespan
- 6-10 years
- Size
- 7-8 cm (3 in)
- Social needs
- Solitary or bonded pair; not a shoaling fish
- Time
- Daily feeding; weekly water testing/changes
- Cost
- Medium
- Diet
- Omnivore (marine pellets, frozen, algae)
Overview
What is this animal?
- 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.
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.
A good fit for
- First-time marine aquarium keepers
- Reef tanks (reef-safe)
- Keepers wanting a hardy centrepiece
- Captive-bred ethical purchasers
Common mistakes to avoid
- Adding fish to an uncycled tank
- Assuming they need an anemone to survive
- No lid - clownfish jump
- Housing two unbonded clownfish that fight
Enclosure
Minimum 75 litres (20 US gallons)
Fine alone or with company. Solitary or bonded pair; not a shoaling fish
- 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.
Supplies
Setup
- Tank, stand and sump
- Return pump and powerheads
- Protein skimmer
- Reef lighting
- Rock and sand
- Salt mix, refractometer and test kits
- Quarantine tank
Ongoing
- Quality small marine pellet
- Frozen mysis shrimp
- Frozen enriched brine shrimp
- Algae-based marine flake
- Vitamin or HUFA soaking supplement
- Small thawing cup and strainer
- Turkey baster for target-feeding
Safe substrate: Aragonite sand · Dry or cured live rock · Bare bottom
Care routine
Daily
- Check salinity, temperature and flow
- Feed small marine portions
- Head-count and look everyone over
- Top up evaporation with fresh water
Weekly
- Service the skimmer and filter socksevery 3 days
- Clean the glass
- Test the water
- Watch the pair's pecking order
Monthly
- Water changeevery 2 weeks
- Calibrate the refractometer
- Check salt, RO/DI and reagents
Less often
- Deep-clean pumps and powerheadsevery 3 months
- Replace RO/DI filter mediaevery 6 months
Vet: Quarterly review with a pair check — every 3 months
Top resources for more info
Independent creators and organisations we would send a friend to. We have no affiliation with any of them, and nothing here is sponsored. Links checked 2026-09-19.
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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.
Is your enclosure big enough?
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.
Bedding and substrate
In a marine system the rock and the sand are life support, and how you start them decides the first six months.
Safe
With a caveat
Never
This is our general list for saltwater fish. We have not built one specific to Clownfish yet.
My kit says 0.25 ppm. Is that dangerous?
A liquid kit measures total ammonia, but only the un-ionised fraction is really toxic, and that fraction is governed by pH and temperature — each whole pH unit multiplies it roughly tenfold. So the same reading can be nearly harmless in one tank and lethal in another; this works out which one you are in.
Compare with other animals
The same axes for every animal, side by side — the way the guides are written makes that a fair comparison rather than two articles.
Clownfish, side by side
Same axes, same care guides — the honest way to choose between types.
See all Clownfish side by side →
