Not furry, but we like them anyway.

Aiptasia-eating Filefish

Acreichthys tomentosus

Also called Bristle-tail filefish, Bristle-tail leatherjacket

SpeciesShort profile

From Indo-West Pacific: Sri Lanka east through Indonesia to New Caledonia and Tonga, north to southern Japan1 2

At a glance the quick version

Length12 to 14 cm1 2 3

Sizesmall

Eats pest Aiptasia anemones

Master of camouflage

Small and peaceful

2 3

Looks how to spot one

Small, thin-bodied filefish with rough skin

A slim, flattened body in mottled green, brown and tan. It can change its colour, pattern and skin texture quickly to blend in with weed and rubble.2 3 4

Coloursgreenbrowntan3 4

Personality what they are like

Peaceful and somewhat shy, though curious. It rarely bothers other fish apart from its close relatives.3 4

Daily activity how busy a day looks

A calm swimmer that likes to hover among rockwork or gorgonians and peek out at its surroundings.4

Grooming and care the hands-on bits

Rated easy to moderate care. Often added to clean up Aiptasia anemones, but use caution in reef tanks since it may nip at soft and stony corals. Acclimate slowly.3 4 2

Home where they are happiest

A tank of at least 30 US gallons (about 115 L) with rockwork for shelter. Saltwater at 22 to 26 °C (72 to 78 °F), pH 8.1 to 8.4, specific gravity 1.020 to 1.025, dKH 8 to 12. Wild fish live on shallow reefs, seagrass and rubble at 2 to 15 m.3 1

Food basics what goes in the bowl

An omnivore. Feed small amounts several times a day: mysis, shaved shrimp, squid, scallop, soaked krill and frozen marine algae. Wild fish eat small bottom animals such as amphipods, worms and molluscs.3 4 1

Company who they like around

Generally solitary. Best kept as a single fish or with peaceful tankmates.1 3

The story where it all began

Linnaeus described the species in 1758. It became popular with reef keepers as a natural way to control Aiptasia, a common pest anemone in aquariums.1 2

Fun facts for the dinner table

1
It can change colour, pattern and even skin texture to hide.2
2
Reef keepers prize it for eating pest Aiptasia anemones.2
3
Wild fish live in shallow seagrass beds as well as on reefs.1
4
Despite its small size it is valued as part of a reef tank's clean-up crew.2

Recognised by the official bits

IUCN Red List: Least Concern (assessed 2015)1

The care rhythm a typical week and year

A typical home-care rhythm for an Aiptasia-eating Filefish. A starting point, not a vet's advice.

FeedingSmall amounts once or twice a dayevery day
Temperature checkevery day
Salinity checkevery week
Top-upTop up evaporation with fresh RO water, not salt waterevery day
Water testevery week
Water changeAbout 10 to 20% of the waterevery 2 weeks
Glass cleanevery week

Owner questions the things everyone asks

How often should I feed my Aiptasia-eating Filefish?

Feed small amounts once or twice a day, as Furry Diary's starting plan suggests. This mimics their natural grazing on small prey. Always check the food label and ask your vet for exact portions.3 4 Pet Wiki plan

What does an Aiptasia-eating Filefish eat, and what should it never eat?

They are omnivores and enjoy mysis, shaved shrimp, squid, scallop, soaked krill, and frozen marine algae. Never feed them anything not listed in their diet, and avoid offering foods that could harm them, consult your vet for a safe list.3 4 1

How much space does an Aiptasia-eating Filefish need?

A tank of at least 30 US gallons (about 115 liters) with plenty of rockwork for hiding is needed. This gives them room to hover and explore calmly.3 1

What temperature, light or water does an Aiptasia-eating Filefish need?

Keep saltwater at 22 to 26°C (72 to 78°F), pH 8.1 to 8.4, specific gravity 1.020 to 1.025, and dKH 8 to 12. They come from shallow reefs, so moderate lighting is fine, but avoid extremes.3 1

How often should I clean an Aiptasia-eating Filefish's home?

Furry Diary's plan suggests a weekly glass clean, a weekly water test, and a 10-20% water change every two weeks. Also top up evaporation daily with fresh RO water. Adjust based on your tank's needs and ask your vet. Pet Wiki plan

Can an Aiptasia-eating Filefish live with others?

They are generally solitary and best kept alone or with peaceful tankmates. They rarely bother other fish but may nip at corals, so caution is needed in reef tanks.3 1

How long does an Aiptasia-eating Filefish live?

Lifespan varies widely depending on care and environment. For a reliable estimate, ask your vet or a good breeder who knows this species well.

Can I handle an Aiptasia-eating Filefish?

Handling is not recommended as it stresses the fish and can damage their delicate skin. Always use a net if you must move them, and keep handling to a minimum.2

Written from the sources on this page, a few checked guides (VCA, ASPCA, RSPCA) and Pet Wiki's own starting care plan. A friendly guide, not a vet's advice.

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Where this comes from

Every fact on this page has a numbered source. Spotted an error? [email protected].

FishBase: Acreichthys tomentosus, Bristle-tail file-fish fishbase.seused for distribution, length, depth, habitat, diet, IUCN status, describer
Wikipedia: Acreichthys tomentosus en.wikipedia.orgused for other names, length, camouflage, Aiptasia control
LiveAquaria: Aiptasia Eating Filefish liveaquaria.comused for aquarium care, tank size, water parameters, temperament, diet, colours
Saltwaterfish.com: Aiptasia Eating Filefish saltwaterfish.comused for care level, temperament, behaviour, diet

Checked 2026-09-30. Text is written in our own words from these sources.