TankBud

Hammer coral

Fimbriaphyllia ancora

Also known as Euphyllia ancora, Anchor Coral, Hammerhead Coral, Euphyllia Hammer

SaltwaterCoral

Hammer coral (Fimbriaphyllia ancora)
Diego Delso · CC BY-SA 4.0

Care at a glance

Temperature
75–81°F
24–27°C
pH
8.1–8.4
Adult size
7.9 in
20 cm
Minimum tank
20 gal
75 L
Temperament
Mostly peaceful
Social behavior
Solitary
Swim level
Bottom
Diet
Photosynthetic
Difficulty
Medium
Breeding
Medium
Rarity
Very common
Reef safe
Reef safe
Family
Euphylliidae
Origin
Indo-Pacific

Overview

The hammer coral is a large polyp stony coral, or LPS, for a reef tank. It is reef safe, and it suits a keeper with some reef experience.

Did you know

A hammer coral's sweeper tentacles carry stinging nematocysts and can extend several inches, mainly after the lights go out.

Caring for the hammer coral

Give a hammer coral moderate light, around 80 to 150 PAR, and low to moderate indirect flow. The flow should make its tentacles sway without blasting them back into the skeleton. Place it anywhere from the sandbed to the lower and middle rockwork, depending on how strong your lighting is.

It needs stable, mature water more than a large volume, and 20 gal (75 L) is the minimum. Keep it at 75 to 81°F (24 to 27°C) with a pH of 8.1 to 8.4. It is photosynthetic and gets most of its energy from symbiotic zooxanthellae, so feeding is optional. It will also capture meaty foods, and you can target feed it once or twice a week to boost growth.

Its sweeper tentacles chemically burn neighbors that are not Euphyllia, so give it at least 6 inches of clearance from other corals. It is fine beside its own kind and generally tolerates other Euphyllia, such as torch and frogspawn, placed right next to it. Fragging is the usual way to propagate it.

Good to know

The hammer coral, Fimbriaphyllia ancora, belongs to the family Euphylliidae and is also listed as Euphyllia ancora. You can identify it by the hammer or anchor shaped tips on its tentacles. The trade also sells it as anchor coral, hammerhead coral or Euphyllia hammer.

In the wild

Hammer corals come from reef slopes and lagoons across the Indo-Pacific. There, their fleshy tentacles sway in gentle current.

Common questions

What size tank does a hammer coral need?

A hammer coral needs at least 20 gal (75 L).

What temperature and pH does a hammer coral need?

A hammer coral is comfortable at 75–81°F (24–27°C) with a pH of 8.1–8.4.

What does a hammer coral eat?

A hammer coral is photosynthetic and gets most of its energy from symbiotic zooxanthellae. It also captures meaty foods, and target feeding once or twice a week can boost its growth.

How big does a hammer coral get?

An adult hammer coral reaches about 7.9 in (20 cm).

Related species