Prickly Octopus

Quick facts

Handling caution: Delivers a venomous bite via its beak; can inject venomous saliva into prey and may bite if handled

Identity

Also known as

Algae Octopus; White-Spotted Octopus; Coconut Octopus; Long Arm Octopus

Synonyms

Abdopus abaculus

Environment

Saltwater

Native to

Indonesia, Philippines, Northern Australia, wider Indo-West Pacific

Habitat

Intertidal reef flats, seagrass beds, sand and rubble down to about 17 m, where it digs a den lined with pebbles and shell fragments

Sourcing

Wild-caught

Conservation

Not Evaluated

Care

Care level

Expert Only

Temperament

Aggressive

Adult size

3 – 10 in (7.6 – 25 cm)

Lifespan

1 – 2 yrs

Min tank

55 gal (208 L)

Growth rate

Fast

Placement

Bottom

Water

Temperature

75 – 79 °F (24 – 26 °C)

pH

8.0 – 8.4

dKH

8 – 12 dKH

Salinity

1.024 – 1.026 SG

Flow

Moderate

Behavior & compatibility

Social

Solitary

Aggression to own kind

High

Active

Daytime

Reef safe

No

Invert safe

No

Shrimp safe

No

Clean-up role

Pest control

Population boom risk

Low

Feeding & breeding

Diet

Carnivore

Foods

Frozen, Live

Breeding type

Direct development

Breeding difficulty

Not bred in captivity

Sexing

Males have a modified third right arm (hectocotylus) used for mating; females are generally larger bodied

Target feeding

Required

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Care guide

Overview

Reaching only about 3 to 10 inches across its arm span, this small octopus grows fast but lives just one to two years. Wild-caught from Indo-Pacific reef flats and seagrass beds, it digs a rubble-lined den by day and hunts crabs and shrimp by night, changing skin texture and color to disappear against the substrate. Suited only to an escape-proof, single-occupant predator tank.

Care

This octopus needs an escape-proof aquarium, since it is a capable crawler and can squeeze through remarkably small gaps in lids and plumbing penetrations. Provide deep sand for digging a den and plenty of rubble or live rock so it can build a lined burrow, its preferred daytime retreat. Stable, pristine water quality with strong filtration and frequent testing is essential, as octopuses are highly sensitive to ammonia, nitrite, and copper. Keep it as the sole tank occupant of note, since its intelligence and predatory habits make mixed-species setups risky for tankmates.

Feeding

Offer live or freshly killed crabs, shrimp, and small mollusks, feeding once daily and adjusting portions to appetite and size. Live fiddler crabs or grass shrimp encourage natural hunting behavior and can be used to enrich an otherwise sedentary daytime routine. Watch for reduced appetite or refusal of food, which often signals stress, poor water quality, or the approach of senescence near the end of its short life.

Tank mates

Best kept alone, as it will consume crabs, shrimp, snails, and small or slow-moving fish sharing its tank. It is not considered reef safe, since it may investigate or disturb corals and will treat most invertebrate tankmates as prey. A species-only or predator tank designed specifically around its needs is the safest approach.

Breeding

Mating behavior is unusually complex for an octopus, including mate guarding, brief transient copulations, and sneaker matings by smaller males that approach a guarded female unnoticed. After laying eggs the female tends and guards the clutch without feeding, and dies shortly after the eggs hatch, consistent with the short single-year lifespan typical of the species. Captive breeding is rarely attempted by hobbyists due to the difficulty of rearing planktonic hatchlings.

Health

Sudden lethargy, pale or blotchy coloration, and loss of appetite are common signs of stress or declining water quality. Because octopuses lack a protective slime coat against many medications, copper-based treatments and other invertebrate-unsafe chemicals must be avoided entirely. A natural decline in activity and feeding near the end of its one to two year lifespan is normal senescence rather than illness.

Sources

1. Abdopus aculeatus - Wikipedia
2. Algae Octopus (Abdopus aculeatus) – Complete Care Guide | Reeflings
3. Algae Octopuses | MarineBio Conservation Society
4. Prickly/Algae Octopus – Violet Aquarium