Colourful red and green macroalgae growing in a reef aquarium

KNOWLEDGE, CULTIVATED.

Algae IDs

Identify common reef growth, choose useful macroalgae and understand what to do when a patch becomes a problem.

Friend: useful when managed. Caution: context or identification matters. Pest: troublesome in a coral display. Photos are reference examples, not species diagnoses.

Start with identification and physical removal. Grazing varies; choose animals for the tank’s long-term needs. Keep nutrients balanced rather than chasing zero, and follow the current product label before treatment.

Written by Christian, Signature FragsLast reviewed:

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Display algae

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Codium fragile in the Birch Aquarium; select a species suitable for your tank temperature.

Codium fragile in the Birch Aquarium; select a species suitable for your tank temperature.

Codium / dead man’s fingers

Caution

Codium spp.

A distinctive ornamental genus; temperature suitability depends on the species.

Display algae · Green macroalgae

Quick ID
Dark green, soft-spongy cylindrical fingers with rounded branching tips.
Benefits / uses
Unusual planted-marine structure; offers shelter and some nutrient uptake.
Problems / risks
Some sold or wild-collected forms are temperate and may decline in a warm reef.
Will anything eat it?
Grazing varies by species; do not assume herbivorous fish will leave it intact.
Products / equipment
Use an identified, aquarium-suitable cultured specimen. No chemical treatment for healthy desired growth.
Common lookalikes
Green sponges and coarse filamentous algae; texture and branching are useful clues.
Care / control
Confirm origin and temperature needs before purchase; give light and flow and remove dying branches.
Research sources

Identification / care reference · Further care / manufacturer guidance

Close-up of yellow and green coral tentacles with pale blue tips

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