Sargassum sp.
| Care Level | Easy to moderate |
| Lighting | Moderate to high |
| Water Flow | Moderate to strong |
| Placement | Display or refugium, on rock |
| Primary Use | Nutrient export & habitat |
| Growth Rate | Moderate to fast |
Overview
Sargassum is a brown macroalgae that grows in bushy, branching fronds dotted with small gas-filled bladders that give it buoyancy — in the wild it forms the famous floating mats of the Sargasso Sea that shelter juvenile fish. In the aquarium it makes an unusual, natural-looking display plant and a capable nutrient exporter.
Care & Placement
Easy to moderate. Give it moderate to high light and good flow, attached to rock in the display or refugium. As a brown alga it is fairly tolerant, and harvesting it regularly is what exports nutrients from the system.
Uses & Nutrient Export
It takes up nitrate and phosphate as it grows, so trimming and removing some exports those nutrients. It also provides shelter and a natural, wild-reef look, and some tangs and other herbivores will graze it.
Propagation & Harvesting
It grows and branches steadily, sometimes tall, so thin and trim it to keep it in bounds and to export nutrients. Inspect new pieces for hitchhikers before adding them.
Cautions
It can grow large and shade corals or other algae below it, so keep it trimmed. Otherwise it is an undemanding, useful macro for a display or refugium.
Frequently Asked Questions
What is Sargassum?
It is a brown macroalgae with buoyant, bladder-dotted fronds — the same genus that forms the floating Sargasso Sea mats. In aquariums it is grown as a natural-looking display plant and a nutrient exporter.
Is Sargassum good for nutrient export?
Yes. It absorbs nitrate and phosphate as it grows, so harvesting it regularly removes those nutrients from the tank, much like other refugium macroalgae.
Will fish eat Sargassum?
Some tangs and other herbivores will graze it, though it is tougher than soft greens like sea lettuce. It works best as a display/refugium plant that also offers grazing and shelter.