Dead Man's Fingers
Codium fragile
Also known as Codium, Sea Fingers, Green Sea Fingers, Green Fleece, Sponge Seaweed
Care at a glance
- Light
- Medium light
- CO2
- No CO₂ needed
- Growth rate
- Medium
- Placement
- Background
- Type
- Macroalgae
- Temperature
- 68–81°F (20–27°C)
- pH
- 8.0–8.4
- Max height
- 9.8 in (25 cm)
- Spread
- 9.8 in (25 cm)
- Nutrient uptake
- Water column
- Growth region
- Submersed
- Difficulty
- Medium
- Origin
- Temperate and subtropical coasts, native to the northwest Pacific around Japan and Korea, now widely naturalized
- Family
- Codiaceae
Overview
Codium is grown as a striking dark green display macroalga that also exports nutrients and shelters pods. It wants moderate to strong reef lighting and moderate to strong flow, and unlike most tropical macroalgae it prefers the cooler end of the marine range and gets unhappy in very warm tanks, so it suits temperate or moderately cool systems best. It attaches to rock rather than rooting in sand, and while it is easy to keep in the right temperature it can be grazed by tangs and other herbivores. It grows at a steadier pace than Caulerpa and does not carry the same overnight crash risk, making it a calmer choice for a display refugium.
In the wild
A dark green macroalga of cooler temperate and subtropical rocky coasts, growing as branching, cylindrical, spongy fingers that fork repeatedly. It attaches to rock and shells in the low intertidal and shallow subtidal and tolerates cooler water than most reef macroalgae, native to the northwest Pacific but now spread worldwide.
Good to know
Codium fragile has a distinctive spongy, felt-like construction: its body is a woven mesh of coenocytic filaments (siphons) whose swollen tips (utricles) pack together to form the solid-looking finger surface. It is a notorious biological invader outside its native range, where it was nicknamed oyster thief because gas trapped in its tissue can float attached shellfish away. It attaches by a basal holdfast rather than roots and feeds from the water column.
Did you know
Codium fragile earned the name oyster thief because pockets of oxygen trapped inside its spongy tissue can generate enough buoyancy to lift an attached oyster or mussel right off the seabed and float it away.
Appears in
Growing Dead Man's Fingers?
Track your planted tank, set reminders and plan your layout.
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