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Shoal & Stem

Flora & Fauna

673 entries β€” care guides, placement tips, and notes from the community

algae
medium

Red Grape Algae

Botryocladia sp.

algaesaltwater

Rare and coveted β€” clusters of translucent, deep-red spherical bladders like bunches of miniature grapes. A showpiece macroalgae that attaches to live rock. Slow-growing and sensitive; requires stable, high-quality water. Highly sought after for display refugia and naturally deters herbivorous fish.

algae
medium

Rhizoclonium

Rhizoclonium sp.

algaefreshwater

Thin, cotton-like green threads that form loose, easily detached clumps β€” often confused with hair algae but coarser and more tangled. Tends to form clumps rather than sheets. Usually caused by excess ammonia or organics in new tanks. Amano shrimp and Florida Flagfish handle it well.

algae
medium

Sargassum

Sargassum natans

algaesaltwater

The iconic free-floating brown macroalgae of the open ocean β€” forms dense golden-brown mats in the Sargasso Sea. In aquariums it anchors to rock or tumbles freely. Hosts an entire ecosystem of cryptic animals (pipefish, frogfish, shrimp) in the wild. Challenging to keep long-term but impressive in large displays.

algae
easy

Sea Lettuce

Ulva lactuca

algaesaltwater

Bright green, tissue-thin sheets of macroalgae familiar on coastlines worldwide. Fast-growing nutrient exporter and a relished food for tangs, urchins, and rabbitfish. Tolerates a very wide temperature and salinity range. Can become weedy if not harvested β€” keep export-focused.

algae
medium

Shaving Brush Plant

Penicillus capitatus

algaesaltwater

Unmistakable calcified macroalgae resembling an old-fashioned shaving brush β€” white stalk topped with a tuft of fine green filaments. Anchors in sandbed. Relatively short-lived (months to a year); when it dies it releases calcium into the water. An endearing curiosity for Caribbean reef displays.

algae
easy

Spirogyra

Spirogyra sp.

algaefreshwater

Bright green filamentous algae with distinctive spiral chloroplasts. In small amounts it's a natural part of the ecosystem and a food source for many invertebrates. Can quickly overtake a tank if nutrients or COβ‚‚ are out of balance. Best controlled by reducing phosphates and manual removal.

algae
hard

Staghorn Algae

Compsopogon sp.

algaefreshwater

Grey-green single strands that branch into antler-like forks β€” often tangled in plant leaves and filter intakes. Like BBA, it signals COβ‚‚ problems. More responsive to spot-treatment with liquid carbon than BBA. Siamese Algae Eaters will consume it.

algae
medium

Thread Algae

Zygnema sp.

algaefreshwater

Very fine, dark green threads β€” slightly stiffer than Spirogyra and less silky. Wraps tightly around plant stems and mosses. Caused by low COβ‚‚ and high light. Siamese Algae Eaters are one of the few fish that readily consume it.

algae
hard

Turf Algae

Various genera

algaesaltwater

A dense mat of mixed short filamentous algae β€” the dominant algae type on wave-swept reef flats in nature. In captivity it traps detritus and is extremely difficult to manually remove. Sea urchins (Diadema, Tuxedo) and tangs are the most effective grazers. Consider a manual scraping plus herbivore-stocking approach.

algae
hard

Water Net Algae

Hydrodictyon reticulatum

algaefreshwater

Remarkable bright green net-like colonies β€” a tessellated honeycomb of cells visible to the naked eye. Beautiful under a microscope but a serious nuisance in garden ponds. Thrives in warm, nutrient-rich water. Manual removal is the primary method as few animals eat it effectively.

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