Najas Indica

Quick facts

Identity

Also known as

Guppy grass; Indian najas; Water nymph

Synonyms

Najas graminea var. indica

Environment

Freshwater

Native to

India, Southeast Asia, East Asia

Habitat

Still and slow-moving freshwater such as ponds, ditches, canals and rice paddies across tropical and subtropical Asia.

Sourcing

Aquacultured

Conservation

Not Evaluated

Care

Care level

Easy

Growth form

Stem

Max height

4 – 23.6 in (10 – 60 cm)

Spread

9.8 in (25 cm)

Growth rate

Fast

Placement

Midground, Background, Floating

Water

Temperature

64 – 86 °F (18 – 30 °C)

pH

6.0 – 7.5

GH

1 – 14 dGH

Flow

Low-Moderate

Light

Low

CO₂

Not needed

Planting

Substrate

Any

Feeds from

Water column

Fertilizer needs

Low

Colors

Green

Feeding & breeding

Propagation

Cuttings

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Care guide

Overview

Thin, bright green stems branch repeatedly into fine, needle-like leaves that form loose, tangled masses either floating at the surface or rooted lightly in substrate. Growth is fast and unfussy, needing only low light and no CO2, so trimming every one to two weeks keeps it from shading out other plants. Brittle stems fragment easily, and each piece roots or drifts to start anew, making overpopulation the main thing to manage.

Care

Guppy grass of this type is kept the same way as its more common cousin Najas guadalupensis, either drifting loose in the water column or pushed lightly into substrate as stem bundles. It asks for nothing special: modest light, no CO2, and whatever nutrients are already present in a typical stocked tank. Because the stems are brittle and snap on contact, expect fragments to break off and root or float elsewhere, gradually filling open water unless thinned back regularly. In nutrient-rich tanks it grows fast enough to shade out plants below it, so periodic removal of handfuls keeps the mass in check.

Planting & trimming

Plant it by simply dropping loose stems into the water to float, or gently press small bundles into the substrate without burying growth points too deeply, since roots are minimal and mainly serve to anchor rather than feed. Trim by hand or scissors on a weekly or biweekly basis, removing 30 to 50 percent of the mass to prevent it from shading lower plants or clogging filter intakes. Never discard trimmings outdoors or into waterways, as the species can naturalize and become invasive.

Fertilizing

No fertilizer dosing is required since the plant draws nutrients directly from the water column rather than through roots. In a lean, low-nutrient aquarium it can actually help by soaking up excess nitrate and ammonia, acting as a natural nutrient sponge. Root tabs are unnecessary and largely wasted on this species, though a general liquid fertilizer in a heavily planted, high-light tank can support faster growth.

Propagation

Propagation is essentially automatic: any stem fragment, even a small broken piece, will continue growing and can root in substrate or keep drifting as a floating mat. Deliberate propagation simply means cutting healthy stem sections and either replanting them in small clusters or letting them float freely to fill in a tank quickly.

Problems

The main issue is not disease but uncontrolled spread, since every broken fragment can start a new plant and a single bunch can overrun a tank within weeks. In low-light or nutrient-poor setups growth slows and stems can thin out or yellow, which usually resolves once light or nutrient levels are raised slightly. It has little tolerance for being kept as a true annual in the wild, so indoor conditions with stable temperature keep it perennial in the aquarium.

Sources

1. Najas indica care: light, CO2 and placement · TankBud
2. Najas guadaloupensis (Guppy Grass) – Care, Propagation, and Aquarium Use
3. Guppy grass care: light, CO2 and placement · TankBud

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