Anacharis Najas (Najas guadalupensis) is one of the most functionally useful plants in the freshwater hobby — a fast-growing, fine-leafed stem plant whose whorled, needle-like leaves are arranged densely along flexible stems that can be planted in substrate, weighted and left free-floating, or allowed to form loose midwater tangles that provide exceptional shrimplet and fry cover. It is positioned differently from Water Sprite in the catalog: where Water Sprite has broader, distinctly fern-like fronds and propagates by adventitious plantlets, Anacharis Najas has very fine, almost hair-like whorled leaves on flexible stems and propagates by fragmentation — individual broken stem sections root and grow independently. The result is a plant with a different texture, a different shelter quality, and a different growth character that fills a distinct niche despite operating in similar functional territory. Nutrient uptake is aggressive, growth rate is rapid, and the fine, dense leaf structure provides biofilm surface area and physical cover that few other plants match. Fully safe with all Neocaridina, Caridina shrimp, and snails.
Not RequiredCO₂
59–82°FTemperature
Low–HighLighting
What to Expect
Growth & Behavior Over Time
Very fine whorled leaves on flexible, fast-growing stems — Anacharis Najas leaves are needle-like and arranged in dense whorls along flexible stems — a leaf form and texture completely distinct from the broader, divided fronds of Water Sprite. The fine, dense whorls give each stem a soft, feathery appearance at close range and a fine-textured mass quality when viewed as a group. Stems are flexible and bend rather than break under water movement, giving planted or floating bunches a gentle, organic response to current.
Among the fastest-growing plants in the catalog — under medium to high light Anacharis Najas puts on several centimetres of new growth per day under good conditions, growing faster than most other stem plants and significantly faster than any rhizome or substrate plant in the catalog. The growth rate is the source of both its primary value — aggressive nutrient uptake — and its primary management challenge — regular trimming to prevent the plant from dominating available space.
Aggressive nutrient uptake — measurable impact on water quality — the rapid growth rate of Anacharis Najas is powered by aggressive uptake of nitrates, ammonia, and phosphates from both the water column and substrate. In shrimp tanks, breeding setups, and new tanks cycling through elevated nutrients, a healthy mass of Anacharis Najas produces a measurable and rapid reduction in nitrate levels between water changes — faster and more immediately than almost any other plant in the catalog.
Works planted or free-floating — different shelter quality in each mode — planted in substrate, Anacharis Najas grows upright and can serve as a background or midground filler. Left free-floating or weighted loosely in the water column, it forms a midwater tangle of fine-leafed stems that provides extremely dense three-dimensional shelter — the hair-like leaves and flexible stems creating a structure that small animals navigate through easily but that provides genuine refuge from visual exposure. Floating bundles in a breeding tank are among the most effective shrimplet cover available.
Propagates by fragmentation — every broken piece grows — unlike Water Sprite which produces adventitious plantlets, Anacharis Najas propagates by fragmentation: any section of stem broken or cut from the main plant is capable of rooting and growing independently. Regular trimming is therefore also regular propagation — cut sections can be replanted, floated, added to breeding setups, or shared. The plant is nearly impossible to accidentally destroy through trimming.
Prefer cooler temperatures than most tropical plants — Anacharis Najas grows across a wide temperature range but performs best and grows most vigorously below 75°F. In tanks running at the higher end of the Neocaridina range (76–78°F) it grows well but slightly less explosively than in cooler conditions. In tanks running at Caridina temperatures (68–72°F) it is one of the most vigorous plants available and an excellent companion for the faster growth rates those conditions support.
How to Set It Up
Getting Started
1Decide on planted or floating mode before introduction — for planted use, strip the lower 3cm of leaves from each stem and push into substrate 2–3cm deep, spaced 2–3cm apart. For floating use, simply place loose bundles on the surface or weight them loosely with a small stone at mid-depth to keep them in the water column. Floating mode maximises shrimplet shelter immediately; planted mode contributes to layout structure and substrate feeding. Both modes work simultaneously in the same tank.
2Trim frequently to manage growth rate — under good conditions Anacharis Najas will put on several centimetres of new stem per day and reach the surface or fill available space within weeks. Check weekly and trim stems before they reach the surface, replanting or floating cut sections rather than discarding them. In tanks where nutrient uptake is the primary goal, allowing a larger mass and trimming less frequently maximises the water quality benefit; in display tanks where layout composition matters more, tighter trimming maintains the form.
3Use floating bundles in breeding setups — for breeding boxes, grow-out tanks, or the main tank during active shrimp breeding, drop loose bundles of Anacharis Najas directly into the setup. The dense midwater tangle provides immediate cover for shrimplets from the moment they are released and accumulates biofilm across the fine leaf surfaces within days. Replace or supplement bundles with fresh trimmings from the main tank regularly to maintain density.
4Minimal fertilization needed — growth is nutrient-driven — in a stocked shrimp tank with regular feeding, the ambient nutrient load from shrimp waste and uneaten food is typically sufficient to fuel Anacharis Najas growth without additional fertilization. In new, lightly stocked, or frequently water-changed tanks, a balanced liquid fertilizer dosed two to three times weekly supports steady growth. The plant will signal deficiency clearly — growth slows and new leaf whorls become sparse — well before any serious problem develops.
💡 Bonus Tip
Anacharis Najas is one of the most effective plants for managing a new tank through the cycling period before livestock is introduced — a large bunch introduced to an uncycled tank absorbs ammonia and nitrates directly as the bacterial colony establishes, acting as a biological buffer that reduces the severity of ammonia and nitrite peaks during cycling. It tolerates the elevated ammonia levels of a cycling tank far better than most shrimp-safe plants and can be removed or reduced once cycling is complete and the bacterial colony is self-sustaining.
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Browse more aquatic plantsPair Anacharis Najas with Water Sprite, mosses, or Vallisneria for a complete planted shrimp setup. Browse our Aquatic Plants collection.
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