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Shoal & Stem

Flora & Fauna

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

fish

Concolor Corydoras

Corydoras concolor

fishfreshwater
plant
medium

Congo Fern

Bolbitis heudelotii

plantfreshwater

Bolbitis is a slow-growing African water fern with elegant, translucent dark green fronds. It attaches to rocks and wood like java fern and anubias, and thrives in moderate flow. CO2 and good lighting significantly improve its growth rate.

fish
easy

Congo Tetra

Phenacogrammus interruptus

fishfreshwater

The Congo tetra is a large, spectacular African tetra. Males develop long flowing fins with a central extension and display an iridescent sheen of blue, gold, and orange across the flanks. A schooling fish that looks magnificent in large planted tanks.

fish
easy

Convict Cichlid

Amatitlania nigrofasciata

fishfreshwater

Black-and-white barred cichlid named for its prison uniform. Extraordinarily hardy and easy to breed — almost too easy. Fierce parents that will defend fry against much larger fish.

fish
medium

Coral Red Pencilfish

Nannostomus mortenthaleri

fishfreshwater

Arguably the most beautiful pencilfish — males blaze vivid red with iridescent blue and white accents. A staple of Amano-style planted tanks. Needs soft, acidic water and live food to colour up.

fish
medium

Corydoras Duplicareus

Corydoras duplicareus

fishfreshwater

Corydoras Duplicareus is a striking species closely resembling C. adolfoi, sharing its orange dorsal blotch and black stripe through the eye, but distinguishable by a broader black flank stripe extending further toward the tail. It originates from the upper Rio Negro system in Brazil and appreciates soft, acidic, warm blackwater conditions. A sought-after species that commands higher prices than common cory varieties.

plant
easy

Creeping Ludwigia

Ludwigia repens

plantfreshwater

One of the most beginner-friendly red plants. Green on top, red underneath — intensity increases with light. Extremely adaptable and fast-growing. Perfect for adding a pop of colour to any planted layout.

fish
easy

Crowntail Betta

Betta splendens 'Crowntail'

fishfreshwater

The Crowntail Betta features dramatically extended fin rays with webbing reduced to one-half or less of the ray length, creating the appearance of a spiky crown. This striking mutation originated in Jakarta in the 1990s and quickly became one of the most popular betta tail types. Males are bold and territorial; their long rays require careful attention to water quality and tank decor to prevent damage.

plant
easy

Cryptocoryne Albida

Cryptocoryne albida

plantfreshwater

A slender Cryptocoryne with narrow, strap-like leaves that range from olive-green to brownish-red depending on light intensity. Submerged leaves are typically narrower and more reddish than the emersed form. Grows to a manageable 15–20 cm and is suited to the midground of smaller tanks or the foreground of larger setups. Tolerates a range of water conditions and is one of the easier narrow-leaved Crypts.

plant
easy

Cryptocoryne Balansae

Cryptocoryne crispatula var. balansae

plantfreshwater

Cryptocoryne Balansae is a dramatic, tall-growing crypt producing strap-like leaves with deeply ruffled, crinkled edges that can reach 40–60 cm in length. Its striking vertical texture makes it one of the most visually distinctive background plants available without requiring high tech. Once established it is robust and spreads into an impressive stand via runners.

plant
easy

Cryptocoryne Beckettii

Cryptocoryne beckettii

plantfreshwater

Cryptocoryne Beckettii is a compact, adaptable crypt producing wavy-edged leaves that range from olive-green on the upper surface to pink-brown or purple on the underside — colouration intensifying under brighter light. It is among the most forgiving crypts, tolerating harder and more alkaline water than most of its relatives. A reliable midground plant for low-tech community tanks.

plant
easy

Cryptocoryne Flamingo

Cryptocoryne wendtii 'Flamingo'

plantfreshwater

Cryptocoryne Flamingo is an eye-catching cultivar with pale pink to deep rose-pink leaves that maintain their colour even in moderate light. A relatively recent cultivar, it adds pastel colour contrast rarely seen in aquatic plants. Hardy and slow-growing like other Cryptocorynes, making it easy to use as a focal foreground or midground accent.

plant
easy

Cryptocoryne Lucens

Cryptocoryne lucens

plantfreshwater

Cryptocoryne Lucens is a small, narrow-leaved crypt with plain bright-green foliage, reaching about 10–15 cm in height. It spreads via runners to form a tidy clump over time and is one of the easiest crypts to keep, tolerating a wide range of conditions including harder water. An excellent choice for foreground or midground planting without the demanding care of more ornate crypt species.

plant
easy

Cryptocoryne Lutea

Cryptocoryne lutea

plantfreshwater

Cryptocoryne lutea is a small to medium-sized crypt producing olive-green to brownish-green leaves with a slightly hammered or textured surface. It is one of the most adaptable and forgiving crypt species, tolerating a wide range of water conditions including moderate hardness and near-neutral pH. Reaching 10–20 cm in height, it works well in the foreground or midground of medium to large planted tanks, spreading via runners into tidy clumps.

plant
easy

Cryptocoryne Nevesii

Cryptocoryne nevesii

plantfreshwater

A small, compact Cryptocoryne with narrow, lance-shaped leaves of uniform mid-green. One of the more underrated compact Crypts, it stays small and spreads slowly via runners to form neat clusters. A good foreground alternative where HC Cuba or Monte Carlo would require CO2.

plant
medium

Cryptocoryne Nurii

Cryptocoryne nurii

plantfreshwater

A highly sought-after Cryptocoryne among collectors, prized for its dramatically patterned leaves featuring brown-green to dark olive surfaces with reddish-brown splotches, spots, and a heavily bullate texture. Multiple forms exist — some have narrow leaves, others broader. Slower and more delicate than common Crypts, it rewards patient keepers with unique, jewel-like foliage. Best maintained in stable, soft, slightly acidic water with minimal disturbance.

plant
easy

Cryptocoryne Parva

Cryptocoryne parva

plantfreshwater

Cryptocoryne Parva is the smallest crypt species, producing narrow, plain-green leaves that rarely exceed 5–6 cm — making it the only crypt truly suitable for a foreground carpet role. Growth is extremely slow even under good conditions; patience of several months is required before carpeting effect appears. It is also the least prone to 'crypt melt' among its genus.

plant
easy

Cryptocoryne Petchii

Cryptocoryne petchii

plantfreshwater

A compact, manageable Cryptocoryne from Sri Lanka with narrow, lance-shaped leaves that can range from olive-green to brownish depending on conditions. Often confused with C. wendtii but distinguished by its shorter stature and slightly narrower leaves. It is very adaptable and tolerates a wide pH and hardness range, making it one of the best Crypts for beginners. Forms attractive rosettes in the foreground or midground of most tanks.

plant
easy

Cryptocoryne Pontederiifolia

Cryptocoryne pontederiifolia

plantfreshwater

A medium-sized Cryptocoryne with broad, oval-to-heart-shaped leaves in a uniform bright green. The rounded leaf form is quite different from most Crypts and adds a distinctive look to the midground. Relatively fast-growing for a Crypt and more tolerant of harder water than many species. An underrated choice that pairs beautifully with more colourful plants like AR or Rotala.

plant
medium

Cryptocoryne Spiralis

Cryptocoryne spiralis

plantfreshwater

Cryptocoryne Spiralis produces unusually long, slender leaves with a finely serrated or slightly twisted edge, giving it a distinctive spiral character unlike most other crypts. Leaves can reach 30–50 cm, placing it firmly in background territory. It prefers softer, slightly acidic water and benefits from CO2 supplementation to sustain its taller, more demanding growth habit.

plant
easy

Cryptocoryne Undulata

Cryptocoryne undulata

plantfreshwater

A versatile mid-sized Cryptocoryne with lanceolate leaves that have attractively undulated margins. Colouration ranges from olive-green to reddish-brown depending on light intensity and water conditions. It is one of the hardiest Cryptocoryne species, tolerating a wider range of pH and hardness than most.

plant
medium

Cryptocoryne Usteriana

Cryptocoryne usteriana

plantfreshwater

A large, majestic Cryptocoryne species with broad, heavily bullate (bumpy-textured) leaves in shades of brown-green with reddish undersides. One of the biggest Crypts available, capable of reaching 50–60 cm in ideal conditions. Best suited to large tanks where it serves as a dramatic centrepiece or bold background plant. Slower to establish than smaller species but extremely long-lived and rewarding.

plant
easy

Cryptocoryne Wendtii

Cryptocoryne wendtii

plantfreshwater

Cryptocoryne wendtii is a popular, low-maintenance rosette plant available in several colour forms from green to brown-red. It may undergo 'crypt melt' when first planted or after water chemistry changes, but almost always recovers. Once established it is resilient and spreads via runners.

plant
easy

Cryptocoryne Wendtii Green

Cryptocoryne wendtii 'Green'

plantfreshwater

The green form of Cryptocoryne wendtii has smooth, bright green leaves with a subtle hammered texture. It is one of the most adaptable crypts available, tolerating a wide range of light, water, and substrate conditions. An excellent beginner midground plant.

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.

plant
medium

Cyperus Helferi

Cyperus helferi

plantfreshwater

Cyperus helferi is the only fully aquatic sedge used in aquascaping. Its long, gracefully arching bright green leaves create a unique grass-like texture that moves beautifully in current. It requires CO2 and fertilisation to grow well submerged.

fish

Delphax Corydoras

Corydoras delphax

fishfreshwater
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.

plant
easy

Dense Waterweed

Egeria densa

plantfreshwater

Classic, bulletproof stem plant with whorls of bright green leaves. One of the best beginner plants — grows rapidly without CO2 and tolerates cool water. Also excellent for goldfish and temperate tanks.

fish
easy

Diamond Tetra

Moenkhausia pittieri

fishfreshwater

The Diamond Tetra lives up to its name — under aquarium lighting the large, iridescent scales along its flanks flash with silver, gold, and green like faceted diamonds. Males develop impressive, elongated dorsal and anal fins as they mature. This Venezuelan species is undemanding and peaceful, making it an eye-catching alternative to more common tetras for medium-sized planted community tanks.

algae
easy

Diatoms (Brown Algae)

Bacillariophyta

algaefreshwater

Brown, dusty coating on glass, substrate, and decorations — the most common algae in newly set-up tanks. Feeds on silicates from tap water and substrate. Almost always disappears on its own within 6–8 weeks once silicates are depleted. Otocinclus catfish and nerites clean it rapidly.

fish
expert

Discus

Symphysodon spp.

fishfreshwater

Discus are considered the 'king of the aquarium' for their spectacular circular shape and brilliant colours. They are demanding fish requiring pristine water, warm temperatures, and frequent water changes. Best kept in species tanks or with very peaceful, warm-water tankmates.

fish
easy

Dojo Loach

Misgurnus anguillicaudatus

fishfreshwater

The dojo loach (weather loach) is a large, eel-like fish famous for becoming more active before changes in barometric pressure. It is extremely peaceful, cold-tolerant, and a hardy beginner fish. It burrows into substrate and requires a tight-fitting lid.

fish
intermediate

Double Tail Betta

Betta splendens 'Double Tail'

fishfreshwater

The Double Tail Betta carries a genetic mutation that splits the caudal fin into two distinct lobes, giving the appearance of two separate tails. This same mutation often also shortens the body and broadens the dorsal fin significantly. Double tails tend to be weaker swimmers than single-tail varieties and are more prone to swim bladder issues; careful feeding with high-quality food helps mitigate this.

plant
medium

Downoi

Pogostemon helferi

plantfreshwater

Pogostemon helferi (Downoi or Little Star) is a distinctive, star-shaped rosette plant from Thailand with deeply ruffled, wavy-edged bright-green leaves radiating from a central crown. It grows low (5–8 cm) and is one of the few compact foreground rosette plants with real textural interest. It requires medium to high light and benefits from CO2 and soft, slightly acidic water. Popular in detailed Iwagumi and Nature Aquarium aquascapes.