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Shoal & Stem

Flora & Fauna

646 entries — care guides, placement tips, and notes from the community

fish
hard

Adonis Pleco

Acanthicus adonis

fishfreshwater

Massive, spectacular pleco with white spots on a jet-black body. One of the largest plecos available, reaching 30+ inches. A monster fish for public-aquarium-scale tanks only.

fish
hard

Altum Angelfish

Pterophyllum altum

fishfreshwater

The largest and most majestic of the Pterophyllum species. Wild altums can reach 50 cm fin-to-fin and require very tall tanks (24 in+ depth). More demanding than P. scalare — needs soft, acidic blackwater conditions and is sensitive to water quality. Best kept in species-only or large blackwater scapes. Wild-caught specimens are more challenging than tank-bred.

shrimp
hard

Bee Shrimp

Caridina cantonensis

shrimpfreshwater

Caridina cantonensis is the base species from which the famous Crystal Red, Crystal Black, and Tiger Bee shrimp have been selectively bred. Wild-type specimens display variable banding of white and translucent to brown, but it is the domesticated varieties that drive the hobby's fascination. All variants require the same exacting soft, acidic water conditions with very low TDS, and are intolerant of copper, fluctuating parameters, or high nitrates.

algae
hard

Black Beard Algae

Audouinella sp.

algaefreshwater

Dense, dark grey-to-black tufts that cling stubbornly to plants, hardscape, and equipment. One of the most frustrating nuisance algaes for planted tank keepers. Caused by CO₂ fluctuation and low or inconsistent carbon dioxide levels. Spot-treat with liquid carbon (Excel) or hydrogen peroxide.

fish
hard

Black Ghost Knifefish

Apteronotus albifrons

fishfreshwater

Jet-black fish with two white bands on its tail. Generates a weak electric field to navigate and communicate. Nocturnal, shy, and sensitive to water quality. Grows large.

algae
hard

Blanket Weed

Cladophora glomerata

algaefreshwater

Dense, rough-textured mats of dark green filaments that blanket pond plants and surfaces. Common in outdoor ponds and highly nutrient-rich tanks. More coarse and branched than soft hair algae. Difficult to eradicate fully — physically remove as much as possible before treating with algaecide or reducing nutrients aggressively.

shrimp
hard

Blue Bolt Shrimp

Caridina cantonensis var. 'Blue Bolt'

shrimpfreshwater

Blue bolt shrimp are a selectively bred Caridina variety featuring a striking white body with vivid blue patches. They require the same pristine, soft, acidic water as other Taiwan bee shrimp. Their dramatic colouration makes them highly sought after by advanced hobbyists.

algae
hard

Blue-Green Algae (Freshwater)

Cyanobacteria spp.

algaefreshwater

A blue-green or red-brown slime that coats the substrate, plants, and glass with a slimy, foul-smelling mat. Technically a bacterium, not true algae. Caused by low nitrates, poor flow, and organic waste. Responds to a 3-day blackout combined with the antibiotic erythromycin or hydrogen peroxide treatment.

algae
hard

Blue-Green Algae (Saltwater)

Cyanobacteria spp.

algaesaltwater

Red, purple, or dark blue-green slime mats that smother the sandbed and rockwork with a slimy, oxygen-depleting film. Technically a bacterium. Caused by low nitrates, poor flow, and high dissolved organics. A 3-day blackout, hydrogen peroxide spot-treatment, and improved flow usually break the cycle.

algae
hard

Bryopsis

Bryopsis sp.

algaesaltwater

Feathery, fern-like dark green algae that is notoriously difficult to eliminate — one of the most persistent reef tank nuisances. Resistant to most herbivores. Best controlled by raising magnesium to 1500–1800 ppm for 2–4 weeks (magnesium treatment). Sea hares will consume it but are not a permanent solution.

algae
hard

Bubble Algae

Valonia ventricosa

algaesaltwater

Iridescent green spheres that appear harmless in small numbers but rapidly colonise rock if left unchecked. Emerald crabs are the most effective biological control. Do not pop bubbles — they release spores and worsen the outbreak. Manual removal requires extracting the entire holdfast; even fragments regrow.

fish
hard

Checkerboard Cichlid

Dicrossus filamentosus

fishfreshwater

Exquisite micro-cichlid with a chequered body pattern and lyre-shaped tail on males. Requires very soft, acidic blackwater conditions. Peaceful but demanding — rewarding for experienced aquascapers.

shrimp
hard

Crystal Black Shrimp

Caridina cantonensis 'Crystal Black'

shrimpfreshwater

Crystal Black Shrimp are selectively bred bee shrimp displaying bold black and white banding — the black body pattern is the inverse of Crystal Red Shrimp. They are graded S to SSS by the clarity and coverage of the white banding. Like all Caridina cantonensis varieties they demand very soft, slightly acidic water with low TDS, and are highly sensitive to copper, temperature swings, and nitrate accumulation. A dedicated shrimp-only tank with buffered aquasoil is strongly recommended.

shrimp
hard

Crystal Red Shrimp

Caridina cantonensis var. Crystal Red

shrimpfreshwater

Crystal red shrimp are selectively bred bee shrimp featuring striking white and red banding, graded S to SSS by pattern clarity. They demand very soft, slightly acidic water and are highly sensitive to temperature swings, dissolved solids, and trace copper. Dedicated shrimp-only tanks using buffered aquasoil are strongly recommended.

fish
hard

Demasoni Cichlid

Pseudotropheus demasoni

fishfreshwater

Stunning deep blue mbuna with pale blue stripes. Extremely aggressive despite its small size — requires a large colony (12+) to disperse aggression. Not for beginners.

algae
hard

Derbesia

Derbesia sp.

algaesaltwater

Fine, fluffy dark green tufts that resemble a softer version of Bryopsis. Often appears in high-nutrient systems and around powerhead intakes. Like Bryopsis it is resistant to most herbivores. Sea hares will consume it; magnesium treatment (1500–1800 ppm) is effective. Reducing phosphate below 0.05 ppm also helps.

algae
hard

Dictyota

Dictyota sp.

algaesaltwater

Flat, iridescent brown-olive blades that spread over rockwork and corals. Beautiful under certain lighting — shimmers blue-green — but highly invasive in reef tanks. Produces chemical deterrents that most fish avoid. Very difficult to eliminate; manual removal stimulates regrowth. Sea urchins (Diadema) and Thalassoma wrasses occasionally graze it.

algae
hard

Dinoflagellates

Symbiodinium / various

algaesaltwater

Brown, stringy, bubble-filled slime that often appears in new reef tanks — frequently mistaken for cyanobacteria. Dinoflagellates ('dinos') form slimy mats that can smother corals and sandbed. Treatment is complex: raise nitrates (>2 ppm), raise phosphates (>0.05 ppm), run extended dark periods, and increase UV sterilisation. One of the most frustrating reef nuisances.

plant
hard

Dwarf Baby Tears

Hemianthus callitrichoides

plant

The smallest aquarium plant in the world, native to Cuba. Forms a dense bright green carpet highly prized in Nature Aquariums and iwagumi layouts. Requires high light, CO₂ injection, and a nutrient-rich substrate to thrive.

fish
hard

Emperor Angelfish

Pomacanthus imperator

fishsaltwater

Majestic large angelfish with electric blue-and-yellow horizontal stripes. Juveniles are black with white rings. Not reef-safe. Requires expert care and very large tanks.

plant
hard

Fissidens Nobilis

Fissidens nobilis

plantfreshwater

Premium aquatic moss with large, firm fronds resembling tiny ferns. Grows slowly but produces a striking, almost sculptural texture unlike any other moss. Attach to rock or wood; requires high flow and clean water.

fish
hard

German Blue Ram

Mikrogeophagus ramirezi

fishfreshwater

The German blue ram is a strikingly coloured dwarf cichlid demanding pristine water quality and warm, soft, acidic conditions. It forms monogamous pairs and will defend a small territory during breeding. Sensitive to poor water quality and temperature fluctuations, making regular water changes critical.

plant
hard

Giant Red Rotala

Rotala macrandra

plantfreshwater

Rotala Macrandra is widely regarded as one of the most beautiful red plants in the hobby, with broad, crinkled leaves that turn vibrant crimson under optimal conditions. It is also one of the most demanding stem plants, requiring very high light, injected CO2, intensive macro and micro nutrient dosing, and soft acidic water — any deficiency quickly manifests as yellowing or failure to colour up. Rewarding for experienced planted tank keepers.

plant
hard

Glosso

Glossostigma elatinoides

plantfreshwater

Glossostigma elatinoides was one of the first foreground carpeting plants popularised by Takashi Amano in the Nature Aquarium style. Its tiny spoon-shaped leaves form an extremely low, dense green carpet when grown under high light with CO2. Without strong light it grows upward rather than creeping, defeating the purpose. It is one of the most demanding carpeting plants but produces one of the most pristine, turf-like results when conditions are ideal.

fish
hard

Gold Nugget Pleco

Baryancistrus xanthellus

fishfreshwater

Gold nugget plecos are stunning loricariids with a dark body covered in bright yellow spots and yellow-tipped fins. They are territorial and require warm, oxygen-rich, fast-flowing water with driftwood. They are algae scrapers that also need protein in their diet.

coral
hard

Goniopora

Goniopora sp.

coralsaltwater

Beautiful coral with long flowing polyps resembling a field of flowers. Historically difficult to keep long-term. Requires stable, high-quality water and moderate flow.

plant
hard

HC Cuba

Hemianthus callitrichoides

plantfreshwater

Hemianthus callitrichoides 'Cuba' (HC Cuba) holds the record as the smallest-leaved aquatic carpeting plant, with each leaf barely 0.5 mm across and stems rarely exceeding 3 cm. Under optimal conditions of high light, CO2, and soft water it forms an impossibly dense, bright-green lawn that is the holy grail of foreground carpets in aquascaping. Extremely demanding and unforgiving of parameter fluctuations, it is best suited to experienced, high-tech setups.

shrimp
hard

King Kong Shrimp

Caridina cf. cantonensis

shrimpfreshwater

Premium Caridina with heavy, mostly black patterning and bold white patches. More black than a standard Crystal Black Shrimp. Requires very soft, acidic water. Prized by serious shrimp breeders.

fish
hard

Leopold's Angelfish

Pterophyllum leopoldi

fishfreshwater

The smallest and rarest Pterophyllum species. Distinguishable from P. scalare by its more elongated body, a distinctive black spot on the dorsal base, and an absence of the pre-dorsal notch. Rarely available in the trade and best kept by experienced keepers. Requires soft, acidic conditions similar to the altum.

algae
hard

Lyngbya

Lyngbya sp.

algaefreshwater

Dark, wiry filaments of cyanobacteria that form dense mats — often mistaken for BBA. Unlike true algae, it can fix atmospheric nitrogen, meaning low nitrogen levels do not suppress it. Produces toxins harmful to invertebrates. Requires the same treatment as blue-green algae: blackout, H₂O₂ treatment, and improved flow.

coral
hard

Montipora

Montipora sp.

coralsaltwater

Montipora is a diverse SPS coral genus second only to Acropora in species diversity, available in plating, branching, and encrusting growth forms in a wide array of colours. It is considered the entry-level SPS coral, more forgiving than Acropora but still demanding stable water parameters, high light, and good flow. Plating Montipora varieties are particularly popular for adding mid-level horizontal structure and bold colour to reef aquariums.

fish
hard

Mudskipper

Periophthalmus barbarus

fishbrackish

Extraordinary amphibious goby that spends most of its time out of water, breathing through moist skin and skipping across mud. Requires a paludarium (half water, half land) setup.

fish
hard

Peacock Bass

Cichla ocellaris

fishfreshwater

Powerful, predatory cichlid with stunning gold and green patterning. Grows large and requires a big tank. Will eat any fish small enough to fit in its mouth.

shrimp
hard

Pinto Shrimp

Caridina cantonensis var. 'Pinto'

shrimpfreshwater

Pinto shrimp are highly prized Taiwan bee variants with bold black and white patterning in distinctive stripe, skunk, or spotted configurations. They are among the most valuable freshwater shrimp in the hobby and require immaculate water quality.

fish
hard

Powder Blue Tang

Acanthurus leucosternon

fishsaltwater

One of the most beautiful tangs with a powder-blue body, yellow dorsal fin and black mask. Prone to ich and disease — best for experienced reef keepers.

plant
hard

Purple Ludwigia

Ludwigia glandulosa

plantfreshwater

Narrow-leaved Ludwigia that turns deep maroon-purple under high light. One of the most intensely coloured aquatic plants available. Slow-growing but spectacular. Requires CO2 and strong light to stay compact.