ORA Marshall Island Red & Green Tenuis Acropora

Quick facts

Handling caution: Branches are sharp and can cause cuts; some skin irritation possible from coral mucus

Identity

Also known as

Marshall Island Tenuis; Red and Green Bottlebrush Acropora

Synonyms

Madrepora tenuis

Environment

Saltwater

Native to

Indo-Pacific, Marshall Islands, Great Barrier Reef, Red Sea

Habitat

Shallow reef flats and upper reef slopes with strong water movement and intense light, typically less than 20 feet deep

Sourcing

Both

Conservation

Near Threatened

Care

Care level

Difficult

Coral type

SPS

Temperament

Peaceful

Growth form

Branching

Adult size

1 – 12 in (2.5 – 30 cm)

Spread

12 in (30 cm)

Growth rate

Moderate

Placement

High

Water

Temperature

76 – 80 °F (24 – 27 °C)

pH

8.1 – 8.4

dKH

8 – 12 dKH

Salinity

1.025 – 1.026 SG

PAR

250 – 450 PAR

Flow

High

Light

High

Reef care

Nutrient preference

Low

Alk/Ca uptake

High

Target feeding

Beneficial

Give it room

3 in (7.6 cm)

Colors

Red, Green, Blue, Multicolor

Feeding & breeding

Diet

Photosynthetic

Foods

Zooplankton, Phytoplankton, Coral food

Propagation

Fragging

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Care guide

Overview

Red branch tips fade into green bases, giving a two-toned bottlebrush colony typical of Marshall Islands broodstock. It is a fast-encrusting SPS best suited to mature systems with intense, stable lighting and strong turbulent flow. Keepers should watch alkalinity and calcium closely, as this tenuis line responds quickly to swings with tissue loss.

Care

Acropora tenuis is a shallow-water branching acro that demands intense, stable lighting and strong, turbulent flow to color up and grow well. It is best kept in a mature, well-established tank since it reacts poorly to swings in alkalinity, calcium, and temperature, sometimes crashing overnight with no obvious warning (rapid tissue necrosis). New frags should be light-acclimated gradually over several weeks by starting them lower in the tank and moving them up as they adjust. Consistent dosing and frequent testing of alkalinity and calcium are more important with this species than with most other corals.

Placement & acclimation

Mount frags securely on rock or a frag plug in an area with high, indirect turbulent flow and strong lighting near the top of the tank. New colonies should be acclimated to light gradually over two to four weeks, starting in a dimmer position and slowly moving upward to avoid bleaching. Once positioned, avoid moving the coral frequently since it is sensitive to changes in flow and light exposure.

Feeding

Most of its nutrition comes from photosynthesis via zooxanthellae, but supplemental feeding of fine zooplankton, amino acids, and coral foods can boost polyp extension and coloration. Feeding is optional rather than required, and stability of water parameters matters more for long-term health than any particular feeding regimen. Target feeding with a turkey baster during low-flow periods can be used occasionally without much added benefit.

Neighbors

Give this coral generous clearance from neighboring corals, especially aggressive LPS such as torch, elegance, or chalice corals, since sweeper tentacles and rapid branch growth can lead to stinging contact. A few inches of open space is usually enough with other SPS like Montipora or Pocillopora, though growth should be monitored over time. It pairs well in mixed SPS displays with similar lighting and flow requirements.

Fragging

Fragging is done by cutting healthy branches with a bandsaw, coral cutters, or shears and mounting the fragments on plugs or rock rubble with cyanoacrylate glue or epoxy. Frags should be kept in stable, lower-flow conditions for the first days to allow tissue to recover and begin encrusting onto the new base. Established colonies used for propagation should be well-fed and under proven-stable water conditions to minimize stress from cutting.

Pests & problems

Sudden tissue loss, often called rapid tissue necrosis, is the most notorious issue with this species and is usually linked to unstable water chemistry rather than a single identifiable cause. Bleaching from excessive or poorly acclimated lighting is another common problem, showing as pale or washed-out branch tips. Acropora-eating flatworms, red bugs, and Montipora-eating nudibranchs can also target this coral and should be checked for regularly.

Sources

1. ORA Marshall Island Red & Green Tenuis Acropora - Bulk Reef Supply
2. Acropora tenuis is both the easiest and the hardest at the same time | Reef Builders
3. Acropora Tenuis Care and Identification Guide | Coral Identifier
4. ORA Red & Green Tenuis Acropora | AlgaeBarn

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