Subclass Alismatidae ( Alismatidae )
Order Alismatales ( Alismatales )
Family Hydrocharitaceae ( Hydrocharitaceae )
Genus Najas — Najas.
Najas or naiad is usually represented here by two species: the modest and graceful Najas guadelupensis and the much longer-leaved, hornwort-like Najas indica. Plants are exclusively aquatic, ranging from green to dark green in color, with a thin branching stem and leaves covered with tiny spines.
Their stem can in some cases become brittle in soft water. However, the plant does not die from this, but only spreads more widely across the body of water. It can be planted in the substrate, forming ascending “fountains” of delicate greenery, but it also develops satisfactorily in a floating state. At temperatures above 25°C, the stem becomes brittle.
Naiads possess two positive qualities: they are very beautiful, and their herbaceous bushes can serve as wonderful material for various compositions. In addition, they are an excellent substrate for eggs during the spawning of many fish species. Cuttings taken from easily broken stems should be planted. The rigid stems of these plants can reach a height of approximately 50 cm. Most naiads prefer soft water. Lighting should be bright, but not excessive.
Common water-nymph, Guadalupe naiad — Najas guadelupensis.
“1” Synonym: Najas microdon. South America. One of the most resilient and undemanding plants. Forms dense delicate thickets in the water column, consisting of thin, highly branching stems (up to 1 m long) with leaves arranged in pairs or threes. Its leaves are linear-oblong, with tiny spines along the edges, leaf blade length up to 4 centimeters, width not exceeding 2.5 millimeters. Leaves are opposite, without visible petioles, sitting so densely at the apexes of the stem that they appear whorled. The coloration is bright green, dark green, sometimes reddish. Branching stems are very brittle.
The wide distribution of this plant is hindered by the extreme brittleness of its stems. This plant possesses significant fragility and incredible vitality. If one attempts to pull this plant out of a home water body, it will begin to break, and every small piece of its stem will produce new shoots that will begin to develop intensively. Water currents carry individual fragments throughout the tank, creating a certain element of untidiness. It is ideal for fish spawning and as a shelter for fry, clearing the water of excess dissolved organics and other nutrients. It has 3 subspecies: — Najas guadelupensis. sp. floridana; — Najas guadelupensis sp. muenscheri; — Najas guadelupensis sp. olivacea.
“2” It can be kept in tropical and moderately warm aquariums. It makes no special demands on water parameters. The plant adapts perfectly to water with a wide range of temperatures – from 18 to 30 degrees. The optimal water temperature is 22-24°C. Water hardness does not play a significant role, but in very soft water, the plant develops somewhat more slowly. The active water reaction can be anything. Water changes 3-4 times a month are desirable, as the naiad grows better in fresh water.
The plant is relatively undemanding regarding lighting conditions; it tolerates prolonged shading, but beautiful thickets of lush green color are formed only under strong illumination. The duration of daylight hours can vary over a very wide range and depends on the illumination of the aquarium.
“4” The root system is poorly developed. The nature of the substrate does not play a significant role for this plant. Naiads can be grown floating in the water column or cultivated without substrate. Najas guadelupensis receives all nutrients from the water, absorbing them through its entire surface. When planted in the substrate, it forms a poorly developed root system, which serves mainly for anchoring the plant and does not participate in nutrition. Mineral fertilization is also redundant for this plant—it gets enough from what enters the water with fish food. Nutrient absorption, photosynthesis, and respiration are carried out across the entire surface of leaves and stems. Therefore, naiads grow particularly well in crystal-clear water, in water currents from filters.
“5” This is one of the most undemanding and resilient plants. It can be grown either floating in the water column or planted in the substrate. In the latter case, a poorly developed root system is formed, which mainly acts as a means of anchoring in the substrate. Placed in the background, the naiad creates a wonderful backdrop for plants with large leaves. It forms dense delicate thickets in the water column. An ideal environment for fry and many aquarium fish is formed within its thickets. It actively influences the metabolism in the aquarium, provides oxygen to aquarium inhabitants, and prepares the water for other, more demanding plants. It easily tolerates transfer from one aquarium to another. Fallen leaves should be removed immediately so they do not pollute the aquarium.
Ease of propagation, rapid growth, and the lack of need for rooting make the naiad not only decorative but also a very useful aquarium plant. Its bunches are placed in a spawning tank, where many small fish reproduce in their thickets, eggs are preserved, and fish larvae and fry hide. Naiad bushes are very fragile; this should be remembered when you are going to transplant or propagate it. It possesses excellent growth rates – up to 15-20 cm per week. It grows well and evenly throughout the year. Najas guadelupensis is so easy to keep that it is recommended for beginner aquarists.
“6” It propagates very easily by cuttings. Branching stems are very brittle. Any fragment gives rise to a new plant—there are buds in the axils of each leaf. It is enough to take one of the numerous shoots and provide it with more or less suitable conditions to get a new dense thicket.
Grassleaf naiad — Najas graminea.
Synonyms: Najas aiagensis, Najas tenuifolla. Distributed in water bodies of England, northern regions of Italy, northern and western Africa, tropical and subtropical Asia. The root system is weak; roots are white and delicate. Stems are long, fragile, and highly branching. Leaves are located on the stem in separate whorls. Each whorl contains 3-6 wavy green linear leaves, 3.5 cm long and 0.3 cm wide. An overgrown adult plant reaches 60 cm in height and is very decorative. Forms dense delicate thickets in the water column.
Placed in the background, it creates a wonderful backdrop for plants with large leaves. It grows better in soft water with moderate warmth and light in fresh water. Lighting should be bright, but not excessive. Propagated by separating side shoots. Cuttings taken from easily broken stems should be planted. It grows evenly throughout the year. It is capable of actively influencing the metabolism in the aquarium, supplying fish with oxygen, and preparing water for many demanding plants.
King’s naiad — Najas indica.
Synonyms: Najas Kingii, Caulinia indica. Southeast Asia. Height up to 50 cm. The root system is poorly developed; roots are thin, white, and very delicate. Stems are thin, long, fairly resilient, and highly branching. Leaves are narrow-linear in shape, up to 2.5 cm long and 0.3 cm wide, translucent, bright green, arranged in whorls of 2-4 leaves. The leaf surface is glossy, margins are toothed. The plant, having grown into a lush bush, is very beautiful.
It can be cultivated in various conditions. Most naiads prefer soft water. Lighting should be bright, but not excessive. Planted in the middle ground. Naiads are not always convenient in trade, because their stem can in some cases become brittle in soft water. However, the plant does not die from this, but only spreads more widely across the body of water. Propagation by stem cuttings. Even tiny pieces of it are viable, quickly producing new shoots that fill the aquarium. pH: 6.0-7.5; T 18-24°C; dH 2-6°.
Ottelia alismoides, Ottelia ulvifolia.
Lagarosiphon madagascariensis, major, miscoides. 
Latest changes and additions were made on December 8, 2012.
