plant Easy level

Najas guadalupensis (Spreng.)

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Southern waternymph, guppy grass, najas grass, common water nymph

Najas guadalupensis is a light to dark green, aquatic plant native to America, where it is widespread in the north, centre, and south. This plant was also introduced into Czechoslovakia, Hungary, Japan, Palestine, Trinidad-Tobago. Najas guadalupensis includes several subspecies.

This is an annual plant, and it grows submerged in aquatic habitat such as ponds, ditches, and streams. The branching stems grow up to 60 to 90 centimeters. The thin, flexible leaves are edged with small, unicellular teeth. Its structure can be fragile, and the plant can take on a messy and tangled look.

This plant is easy to maintain in a biotope aquarium, as it doesn’t require special care or bright lighting. It is rather fit to be included in the aquarium as a bottom or floating, decorating plant, to be placed in the middle or background of the tank.

Submitted by
Eleonora Pasquariello
11.9126825, -85.9296265
Geographical region
Central America
Drainage Basin
Caribbean Sea via Rio San Juan
River catchment
Water body type
Tectonic Lake
Water body name
Water body part
Open water
Water body course
Water body: tributary of
Tributary name
Type locality
Colombia, Andes, Llanura del Caribe, Valle del Cauca.
Conservation status/IUCN Red List
Not Evaluated (NE)
Listed in CITES

Water Chemistry

Water information

Water type
Fresh water
Water color
Clear water
Water transparency
Concentration of sediments
Water temperature
20-26 °C
Water flow/curent

Chemical parameters

3-20 mg/l
Dissolved Oxygen


Plant form
Plant type
Plant size
60-90 cm
Plant growth rate
Plant light demand
Aquarium equipment

In the biotope aquarium, this plant does not requite a substrate rich of nutrients. Najas guadalupensis needs low to medium lighting and low, if needed, CO2 addition. Being a rather fragile plant, it shouldn’t be placed close to the filter.


Plant care

This plant can be added to the aquarium tank as a bottom or floating plant. Anyways, it should be managed with care, because the stems and leaves are thin and fragile. If the plant is cultivated as floating, it shouldn’t be kept too close to the light, or the leaves will burn.

Being a fragile plant, Najas guadalupensis might break. The broken fragments might root on the bottom and grow other plants. This plant does better in polluted waters; so, NO3 and PO4 can spur its growth. A proper fertilization can increase the plant’s growth and quality. Furthermore, it is a plant that grants shelter to small fish and fry.

Water care

The optimal temperature conditions for growing this plant is 20 to 26°C. The pH values should be kept between 6.0 and 8.0. Najas guadalupensis can also easily tolerate soft or hard water. Water hardness tolerance range is between 2 to 20 GH.