Clownfish (Anemonefish) Care Guide

Quick Facts

• Family: Pomacentridae (damselfish family); genus Amphiprion (around 28–30 recognised species) plus the single species of the genus Premnas (Maroon Clownfish)
• Origin/Native Range: Indo-Pacific tropical reefs, from the East African coast and Red Sea across the Indian Ocean, through the Coral Triangle, to the Great Barrier Reef and out to the Pacific islands – exact range varies by species
• Adult Size Range: Approximately 7.5–18 cm (3–7 in) depending on species; females are always larger than males
• Diet: Omnivore – meaty foods (mysis shrimp, brine shrimp) plus algae/spirulina-based foods
• Temperament: Peaceful to semi-aggressive; territorial around a host anemone or chosen territory, with aggression generally increasing as the fish matures and grows
• Minimum Tank Size: 75 L (~20 US gal) for a single fish or bonded pair of a smaller species; 115 L (30 US gal) or more strongly recommended for Maroon, Tomato, Saddleback and other larger or more territorial species
• Water Temperature: 24–28°C (75–82°F)
• Specific Gravity/Salinity: 1.020–1.025 (aim for 1.023–1.025 in a mixed reef system)
• pH: 8.1–8.4
• Lifespan: Typically 6–10 years in captivity; well-maintained specimens are regularly reported to reach 15–20+ years
• Experience Level: Beginner-friendly for most species; intermediate for adult Maroon, Tomato, Saddleback and Clarkii due to territorial behaviour as they mature

Overview and Natural Origin

Clownfish, also known as anemonefish, are among the most recognisable and popular fish in the marine aquarium hobby. All 30-odd species belong to the damselfish family Pomacentridae, sitting within the genus Amphiprion – with a single notable exception, the Maroon Clownfish, which is the sole member of the closely related genus Premnas and is distinguished by a sharp, venomous-looking cheek spine beneath each eye. Clownfish are found exclusively in the tropical waters of the Indo-Pacific, with individual species occupying more specific ranges within that region – from the East African coast and Red Sea, across the Indian Ocean and the biodiverse "Coral Triangle" of Indonesia, the Philippines and Papua New Guinea, to the Great Barrier Reef and out into the Pacific as far as French Polynesia. No clownfish species occurs naturally in the Atlantic or Caribbean.

In the wild, clownfish are famous for their obligate or near-obligate symbiotic relationship with large sea anemones of the genera Entacmaea, Heteractis, Stichodactyla and Cryptodendrum. The fish acquire a protective mucus coating that makes them immune to the anemone's stinging nematocysts, allowing them to shelter within the tentacles where few predators dare follow. In exchange, the clownfish defend the anemone from butterflyfish and other polyp-eating predators, remove debris and dead tissue, and their constant movement improves water circulation and oxygenation around the anemone's tentacles and gut cavity. Different species show different degrees of host specificity: some, such as Clark's Clownfish (Amphiprion clarkii), are generalists that will host in around ten different anemone species, while others, such as the skunk clownfishes, are far more selective.

Clownfish also display one of the most striking reproductive strategies in the fish world: protandrous sequential hermaphroditism. Every clownfish is born male. Each anemone or territory typically supports a small social group with a strict size-based dominance hierarchy: the single largest fish transforms into the group's breeding female, the second-largest becomes the breeding male, and any remaining juveniles remain sexually immature, non-breeding males that wait their turn. If the dominant female dies or is removed, the breeding male undergoes a physiological sex change and takes her place, while the next-largest male is promoted to breeding male. This hierarchy is maintained largely through size-based aggression rather than fighting to the death, and it is the reason hobbyists are advised to buy captive-bred pairs or allow two juveniles to grow up together rather than combining two adult, already-sexed fish.

Appearance and Size

Clownfish share a broadly similar body plan: a deep, laterally compressed, oval body with a blunt snout, small mouth, and a thick protective layer of mucus. Colouration is typically some combination of orange, red, maroon, brown or near-black, broken by one to three vertical white (occasionally pale blue-white) bars outlined in black – the number and position of these bars is one of the main ways the various species are told apart in the field. Selective captive breeding, particularly by aquaculture producers, has also produced a large range of designer colour morphs of the Ocellaris Clownfish in particular – including "Snowflake", "Storm", "Platinum", "Black Ice", "Domino" and similar lines – which display irregular white patterning, extended white areas, or near-total loss of orange pigment, none of which occur in wild populations.

Adult size varies meaningfully across the group. The smallest species stocked by most retailers, the Pink Skunk (Amphiprion perideraion) and Orange Skunk (Amphiprion sandaracinos) Clownfish, top out around 10–11 cm (4–4.3 in) for females, with males noticeably smaller. Standard favourites such as the Ocellaris and Percula Clownfish sit in the middle of the range at roughly 7.5–11 cm (3–4.3 in). At the top end, the Maroon Clownfish is the giant of the group, with females reaching up to 18 cm (7 in) – nearly double the size of the smallest species – while males remain considerably smaller and less deeply coloured. As with all clownfish, females are always the larger, more dominant sex in a pair.

Species Commonly Stocked

Nick's Aquarium Oceanarium Terrarium regularly stocks the following clownfish/anemonefish species, spanning both wild-caught and captive-bred/tank-raised stock, plus a wide range of captive-bred designer colour forms of the Ocellaris and Percula Clownfish:

• Ocellaris Clownfish (Amphiprion ocellaris) – also called the False Percula Clownfish. Grows to roughly 7.5–9 cm (3–3.5 in), occasionally larger. Native to the Western Pacific and Eastern Indian Ocean. Distinguished from the True Percula by thinner black outlines on its white bars and 11 dorsal spines (versus 10 in A. percula). The most widely available, hardiest and most beginner-friendly clownfish in the hobby, and the species behind the large majority of designer colour morphs on the market, including the Black & White, Snowflake, Storm-line, Platinum, Black Ice, Black Lightning, Domino and Snow Onyx varieties.
• Percula Clownfish (Amphiprion percula) – the "True Percula". Reaches up to around 11 cm (4.3 in), though typically stays closer to 7.5–8 cm (3 in) in aquaria. Native to a narrower range than Ocellaris – the northern Great Barrier Reef, Papua New Guinea, New Britain, the Solomon Islands and Vanuatu. Told apart from Ocellaris by noticeably thicker black outlining on its white bars and by having one fewer dorsal spine. Includes Misbar and Picasso-patterned variants, in which the bars are broken or irregular.
• Maroon Clownfish (Premnas biaculeatus) – the largest and most robust clownfish, with females reaching up to 18 cm (7 in); males are smaller and typically brighter red. The only clownfish placed outside the genus Amphiprion, easily identified by the sharp spine on each cheek (handle with care when netting). Deep maroon to near-black base colour with three white to gold bars; popular designer lines include Gold Stripe, Gold Nugget and Lightning Maroons. By far the most territorial and aggressive clownfish commonly available, especially as adults.
• Pink Skunk Clownfish (Amphiprion perideraion) – a small, pale pink species with a single fine white stripe running from the top of the head to the tail, reaching a maximum of about 10 cm (4 in). Native from the Ryukyu Islands south to the Great Barrier Reef, and from southeastern Thailand east to Samoa. One of the gentlest, most peaceful clownfish species, staying close to its host and rarely showing aggression even to tankmates.
• Orange Skunk Clownfish (Amphiprion sandaracinos) – closely related to the Pink Skunk but brighter orange with a broader white dorsal stripe. Females reach around 11 cm (4.3 in); males are considerably smaller, at 3–6.5 cm (1.2–2.6 in). Found through the Coral Triangle (Philippines, Indonesia, New Guinea) and out to northwestern Australia and the Ryukyu Islands. Generally non-aggressive and a specialist host of Merten's carpet anemone in the wild.
• Clarkii Clownfish (Amphiprion clarkii) – also called Clark's Anemonefish. One of the largest and hardiest Amphiprion species, reaching up to 15 cm (6 in). Has by far the broadest natural range of any clownfish, from the Persian Gulf and Red Sea across the Indo-Australian Archipelago to Melanesia, Micronesia, Taiwan and southern Japan – and the widest anemone host range, associating with around ten different anemone species in the wild. Extremely adaptable and disease-resistant, but becomes noticeably more territorial and semi-aggressive as it matures and grows.
• Barrier Reef Clownfish (Amphiprion allardi) – also known as Allard's Clownfish. Reaches a maximum of about 14 cm (5.5 in). Note that despite the common trade name used in this range, this species is not native to Australia's Great Barrier Reef – its true range is the East African coast between Kenya and Durban, South Africa, within the wider Indo-Pacific/Western Indian Ocean region. Dark brown to near-black body with two white bars edged in black and an orange-tinted caudal fin.
• Fire Clownfish (Amphiprion melanopus) – also widely known as the Cinnamon Clownfish. Grows to around 12 cm (4.7 in). Native to the Western Pacific, from the Great Barrier Reef north to the Marshall Islands and Guam, and from New Guinea and Vanuatu west to eastern Indonesia. Deep red-orange body with mahogany sides, a single white head bar, and typically black pelvic and anal fins. Confident and hardy, but can become territorial as an adult, particularly toward other clownfish.
• Saddle Back Clownfish (Amphiprion polymnus) – named for the broad, irregular white "saddle" patch across its mid-back, set against deep orange-brown to near-black colouration. Reaches roughly 12–14 cm (5–5.5 in). Found throughout the Indo-Pacific, typically over sandy-bottomed lagoons and coastal reef flats rather than hard reef structure. Semi-aggressive and noticeably bolder than Ocellaris or Percula Clownfish, doing best with ample swimming space and carefully chosen tankmates.
• Sebae Clownfish (Amphiprion sebae) – a larger, hardy species averaging around 12 cm (5 in), with some individuals reported larger. Native to the Indian Ocean, including the Andaman Sea, Bay of Bengal and surrounding coral reef and lagoon habitats. Dark brown to black body with a single broad white head bar and a yellow to orange tail. Generally peaceful but territorial around its chosen anemone or shelter site.
• Tomato Clownfish (Amphiprion frenatus) – deep tomato-red to brick-red body with a single white head bar in adults (juveniles may show additional, fading bars). Can reach up to around 14 cm (5.5 in) in the wild, though captive specimens more commonly settle around 7.5–9 cm (3–3.5 in). Native to the Western Pacific. An adaptable, hardy feeder, but well known for becoming increasingly territorial and even aggressive as it matures, particularly toward other clownfish and similarly-shaped, more peaceful damselfish.

Tank and Water Requirements

Most single clownfish or bonded pairs of the smaller, calmer species (Ocellaris, Percula, Pink Skunk, Orange Skunk) can be comfortably housed in tanks from 75 L (20 US gal) upward, provided filtration and water quality are well maintained. Larger, bolder or more territorial species – Maroon, Tomato, Clarkii, Saddleback and Sebae Clownfish – are better suited to 115 L (30 US gal) or larger, both to give the fish room to establish a territory without becoming overly possessive of the whole tank, and to make it easier to house them alongside other fish. As with all marine fish, tank size should also account for any tankmates, live rock, and (if included) the mature footprint of a host anemone, which can occupy a substantial area of the aquarium.

Target stable water parameters of 24–28°C (75–82°F), specific gravity of 1.020–1.025 (1.023–1.025 is preferable in a reef system to suit corals and other invertebrates), and pH of 8.1–8.4. Clownfish are among the hardier marine fish with respect to water quality once established, but like all saltwater species they require a fully cycled tank with zero detectable ammonia and nitrite, and should always be acclimated slowly using a drip method to avoid osmotic shock. Clownfish are reef-safe and will not harm corals, clams or most invertebrates, making them an excellent centrepiece for a reef aquarium as well as a fish-only or FOWLR (fish-only-with-live-rock) system.

A host anemone is not required to keep clownfish successfully in captivity – this is one of the most persistent myths in the hobby. Clownfish will thrive, feed, colour up and even breed in a well-set-up aquarium without any anemone present, and will typically substitute a piece of live rock, a powerhead, a coral (such as a large-polyped stony coral or leather coral), or even a corner of the glass as a surrogate "host" and territory. Keeping a host anemone is an advanced undertaking in its own right – most anemone species have specific, demanding lighting, flow and water quality requirements, and pairing a clownfish with an unsuitable or poorly kept anemone can harm both animals. Anemones should only be added by experienced reefkeepers once the tank is fully mature, and never purely to "complete the look" of a clownfish tank.

Diet and Feeding

Clownfish are omnivores and, as a group, are among the least fussy eaters in the marine hobby, readily accepting frozen mysis and brine shrimp, marine flake, pellet food and other prepared diets. In the wild their diet includes zooplankton, small crustaceans, algae and, for some species, the mucus and leftover food scraps of their host anemone. In captivity, feed a varied diet combining meaty frozen or live foods (mysis shrimp, enriched brine shrimp, chopped seafood) with algae- or spirulina-based foods to maintain healthy colouration and support the beneficial gut symbionts anemonefish rely on. Most keepers feed small amounts two to three times daily, offering only what the fish can consume within a minute or two to avoid fouling the water. Vitamin-enriched foods and occasional garlic-soaked feedings are commonly used to boost immune function, particularly for recently imported wild-caught stock.

Temperament and Tank Mate Compatibility

As a group, clownfish are rated peaceful to semi-aggressive, and are generally considered excellent, hardy community fish that get along well with the vast majority of other reef-safe marine species – wrasses, gobies, blennies, tangs, dwarf angelfish and most other non-aggressive fish are all suitable tankmates. However, temperament varies considerably between species and, importantly, changes with age and size. Juvenile clownfish of almost any species are typically mild-mannered, but as they mature and claim a territory (whether around an anemone, a piece of rock, or simply a corner of the tank), most species become progressively more assertive in defending that space.

Some species are markedly more territorial than others. The Maroon Clownfish has by far the worst reputation in the hobby for aggression – adults, and especially the dominant female, will vigorously defend their territory against other clownfish and can bully smaller or more timid tankmates, so Maroons are usually best kept as a single specimen or an established, already-bonded pair rather than introduced alongside other clownfish species. The Tomato Clownfish follows a similar pattern: docile as a juvenile, but noticeably more territorial and confident as an adult, particularly toward other clownfish and toward smaller, more peaceful, similarly-shaped fish that can trigger its territorial instincts. Clarkii, Saddleback and Sebae Clownfish also tend to become bolder and more assertive with size, though generally less extreme than Maroon or Tomato. By contrast, the Pink Skunk and Orange Skunk Clownfish remain among the most consistently peaceful and shy clownfish throughout their lives.

As a general rule, only keep one clownfish species per tank unless the aquarium is large and aquascaped with multiple well-separated territories, and never house two unrelated clownfish of similar size together, as this frequently results in the larger fish harassing or killing the smaller one as they compete for dominance in the group hierarchy. The safest way to keep two or more clownfish together is to purchase an already bonded, captive-bred pair, or to raise two small juveniles together from the outset so the size-based pairing hierarchy establishes naturally. As noted above, none of the species listed require a host anemone, and wild-caught individuals collected from a host in the ocean will settle into anemone-free aquaria without lasting ill effects – captive-bred and tank-raised stock, which make up an increasing share of the trade, have typically never encountered an anemone at all and show no dependency on one.

Breeding Notes

Clownfish are, as a group, among the most commonly and successfully captive-bred marine aquarium fish in the world – a status they owe to their manageable size, willingness to pair and spawn readily in captivity, and a larval stage that, while still demanding, is more tractable to rear than that of most other marine species. This makes them a mainstay of marine fish aquaculture worldwide, and a large proportion of clownfish sold today, particularly designer colour morphs, are tank-raised rather than wild-caught.

Once a pair has bonded – the larger fish established as the breeding female and the next-largest as the breeding male, per the protandrous hermaphroditism described above – spawning can occur roughly every couple of weeks in stable, well-fed conditions. The pair selects a hard, flat surface within their territory to spawn on, very often a rock, coral skeleton or piece of hardscape situated close to the host anemone (where one is present) or their chosen substitute territory. The female deposits several hundred to over a thousand adhesive eggs in a neat patch, which the male then fertilises. From that point, parental care falls almost entirely to the male: he fans the egg patch continuously with his pectoral fins to keep it oxygenated and free of debris, and picks out any dead or fungus-affected eggs to protect the health of the clutch. Eggs typically hatch 8–10 days after spawning, with the precise timing driven mainly by water temperature, and hatching usually occurs after the aquarium lights go out, when planktonic predation risk on the emerging larvae is lower.

Successfully raising the resulting larvae to a juvenile stage is a specialised undertaking best suited to dedicated hobbyist breeders or aquaculture facilities rather than a display tank: newly hatched larvae are extremely small, cannot use a standard filtered aquarium (where they risk being drawn into pumps and filtration or lost to predation), and require a separate rearing setup with cultured live rotifers and, later, newly hatched brine shrimp as first foods, gentle aeration, and very stable water quality over several weeks of metamorphosis before they settle into their juvenile form.

Common Health Issues

Clownfish are generally hardy fish, but like all marine species they are vulnerable to the standard suite of saltwater ailments, and proper quarantine of all new stock is strongly recommended before introduction to a display tank or reef system.

• Brooklynellosis ("Clownfish Disease") – caused by the ciliated protozoan parasite Brooklynella hostilis, this is the single disease most strongly associated with clownfish and can move extremely fast, particularly through freshly imported wild-caught stock, where entire shipments have historically been lost to it. Early signs are subtle – clamped or slightly folded fins and lethargy – before progressing rapidly to excessive mucus production, laboured/rapid breathing, loss of colour, loss of appetite and death, sometimes within hours once advanced. Because of the speed of onset, prompt treatment (commonly formalin dips or a course of chloroquine in a dedicated hospital tank) is essential, and purchasing captive-bred or well-acclimated tank-raised stock substantially reduces the risk compared with fresh wild imports.
• Marine Ich (Cryptocaryon irritans) – presents as fine white salt-like spots across the body and fins, along with flashing (scratching against rock or substrate), increased respiration and appetite loss. Treated with a copper-based medication, hyposalinity, or tank transfer method in quarantine; the parasite's free-swimming stage means the display tank typically needs a fallow period to fully eradicate it.
• Marine Velvet (Amyloodinium ocellatum) – a dinoflagellate parasite causing a fine, dusty gold-to-white sheen on the skin, rapid gilling, and rapid deterioration; considered one of the most lethal marine fish diseases and requires urgent treatment, usually copper therapy in a hospital tank.
• Head and lateral line erosion (HLLE) – pitting around the head and along the lateral line, generally linked to nutritional deficiencies (particularly vitamin and lack of dietary variety) and/or poor water quality over time; addressed with a more varied, vitamin-enriched diet and improved water conditions.
• Physical injury from netting – a Maroon Clownfish–specific hazard: the sharp cheek spines characteristic of the genus Premnas readily snag aquarium nets, causing stress and potential injury to the fish; a specimen container or cup is the safer way to catch or move this species.

As with all marine fish, the best defence against disease is a properly cycled, stable aquarium, a minimum 2–4 week quarantine period for all new arrivals, and a varied, high-quality diet to support the fish's immune system.

Sources: Saltwater Aquarium Blog (Ocellaris Clownfish Care Guide; Clownfish Breeding & Egg Development Guide); LiveAquaria (Maroon Clownfish Species Profile; Ocellaris vs. Percula Clownfish Differences); Fishlore (Maroon Clownfish Care); Reef Builders (Tomato Clownfish; Amphiprion perideraion; Brooklynellosis); Bulk Reef Supply (Clarkii Clownfish Care Guide; Saddleback Clownfish Care Guide); Reeflings (Sebae Clownfish Care Guide); FishBase (Amphiprion percula; Amphiprion clarkii); Australian Museum (Sex Change in Clownfish); Wikipedia (Cinnamon Clownfish; Allard's Clownfish; Orange Skunk Clownfish).

Frequently Asked Questions