TankBud

Elephant ear mushroom

Amplexidiscus fenestrafer

Also known as Giant Cup Mushroom, Giant Elephant Ear, Giant Disc Anemone, Giant Mushroom Anemone

SaltwaterCoral

Elephant ear mushroom (Amplexidiscus fenestrafer)
Ahmed Abdul Rahman for MDC Seamarc Maldives · CC BY-SA 4.0

Care at a glance

Temperature
75–81°F
24–27°C
pH
8.1–8.4
Adult size
13.8 in
35 cm
Minimum tank
20 gal
75 L
Temperament
Aggressive
Social behavior
Solitary
Tankmates
With caution
Swim level
Bottom
Diet
Photosynthetic
Difficulty
Medium
Breeding
Medium
Rarity
Common
Reef safe
Reef safe
Family
Discosomidae
Origin
Indo-Pacific reefs, in shallow, often turbid lagoons and tide pools, from Southeast Asia to Australia

Overview

The elephant ear mushroom is the giant of the mushroom corallimorphs, and a real predator rather than just a passive filter feeder. It is best with a little experience.

Did you know

The elephant ear mushroom looks and acts like a sea anemone, right down to luring and swallowing small fish. It is not an anemone at all but a corallimorph. It can seal its disc shut around prey in well under three seconds, fast enough to catch a curious clownfish.

Caring for the elephant ear mushroom

Give the elephant ear mushroom moderate to fairly strong light, roughly 150 to 300 PAR, with gentle, indirect flow rather than a direct blast. Place it in a low, open spot on the sandbed or lower rockwork. Leave generous clearance on all sides, because a healthy disc can open to 30 cm or more across.

Keep the water at 75 to 81°F (24 to 27°C) with a pH of 8.1 to 8.4, in at least 20 gal (75 L). Like other mushroom corallimorphs, it hosts zooxanthellae and gets most of its everyday energy from light. It only needs a light supplemental feeding of a piece of fish, shrimp or clam every couple of weeks.

Small fish and shrimp that land on the disc, including unwary clownfish, can trigger it to fold shut around them and slowly digest them. Keep it well away from nano fish, cleaner shrimp and other small livestock, rather than in a busy community reef. It is best kept as a specimen piece with open space around it. It will not sting or chemically bother neighboring corals, as long as they sit too far away to be brushed by the disc.

Good to know

Amplexidiscus is a monotypic genus, meaning fenestrafer is the only species in it. It sits in the corallimorph family Discosomidae, alongside Discosoma and Rhodactis. Its name translates roughly to enfolding plate, for the way the wide, flat oral disc folds inward and seals shut.

In the wild

Amplexidiscus fenestrafer lives on shallow, often turbid reef flats and lagoons in the Indo-Pacific, from Southeast Asia to Australia. It is found from the shallows down to about 18 m. There it sits as a solitary, saucer-shaped disc on rock or rubble.

Common questions

What size tank does an elephant ear mushroom need?

An elephant ear mushroom needs at least 20 gal (75 L).

What temperature and pH does an elephant ear mushroom need?

An elephant ear mushroom is comfortable at 75–81°F (24–27°C) with a pH of 8.1–8.4.

What does an elephant ear mushroom eat?

An elephant ear mushroom gets most of its everyday energy from light, through its zooxanthellae. It only needs a piece of fish, shrimp or clam every couple of weeks. It will also catch small fish and shrimp that land on its disc.

How big does an elephant ear mushroom get?

An adult elephant ear mushroom reaches about 13.8 in (35 cm).

Related species