Red Spike Gracilaria is a fast-growing red macroalgae valued for dependable nutrient export, clean growth habits, and broad compatibility with marine aquariums. Scientifically identified as Gracilaria blodgettii, this Rhodophyta species is commonly maintained in refugiums where it helps reduce nitrate and phosphate while supporting pod populations and herbivorous grazers. Its firm, cylindrical branching structure resists breakage, making it easier to manage than softer red macroalgae.

Aquarists select Red Spike Gracilaria when they want effective nutrient control without invasive spread. It adapts well to a range of reef lighting and flow conditions, making it suitable for both new and established systems. 

Appearance

Red Spike Gracilaria forms upright, bushy clusters with firm, cylindrical branches that may appear slightly spiked at the tips. Color ranges from deep red to reddish-brown depending on nutrient levels and lighting intensity. Healthy specimens retain structure and opacity rather than becoming limp or translucent.

Care & Requirements

Red Spike Gracilaria performs best in stable marine systems with moderate lighting and gentle to moderate water movement. It does not attach to rock or substrate and should be loosely placed in a refugium chamber or secured to prevent excessive shading. Consistent access to dissolved nutrients supports steady growth and predictable nutrient export.

Standard reef lighting is sufficient, and extreme intensity is unnecessary. Routine trimming promotes compact growth and prevents detritus accumulation within the algae mass. While iron and trace elements can enhance coloration, most systems provide adequate nutrients without dedicated supplementation.

Does Red Spike Gracilaria require high-intensity lighting?
Moderate reef lighting supports healthy growth without the need for specialized fixtures.

Can it be kept free-floating in a refugium?
Yes, it naturally remains unattached and free-floating.

Tank Mates & Compatibility

Red Spike Gracilaria is compatible with reef-safe fish, corals, and invertebrates. It provides shelter and grazing surfaces for copepods and amphipods, supporting natural food chains. Some herbivorous fish may graze on the algae, which can be beneficial if managed.

Avoid housing with aggressive or constant algae grazers if sustained growth is the goal. Refugium placement allows controlled access while maintaining nutrient export efficiency.

Is Red Spike Gracilaria safe in coral reef tanks?
Yes, it does not release toxins or harm corals.

Will herbivorous fish consume it?
Some species may graze on it intermittently.

FAQ

Is Red Spike Gracilaria the same as other Gracilaria species?
No. While related, individual Gracilaria species differ in structure, growth rate, and aquarium performance. Red Spike Gracilaria specifically refers to Gracilaria blodgettii, known for firmer branching and controlled growth.

Is Red Spike Gracilaria classified as red algae?
Yes. It belongs to the Rhodophyta group, characterized by red pigmentation and efficient photosynthesis under reef lighting.

How does Red Spike Gracilaria help with nutrient control?
As it grows, it absorbs nitrate and phosphate from the water, helping stabilize nutrient levels when harvested regularly.

Does this macroalgae require dosing or fertilizers?
Most reef systems supply sufficient nutrients naturally, though iron may enhance coloration.

How fast does Red Spike Gracilaria grow in a refugium?
Growth is moderate and depends on lighting, nutrients, and trimming frequency.

Is Red Spike Gracilaria edible?
While some Gracilaria species are used for food and agar production, aquarium specimens should not be consumed.