Subclass Alismatidae ( Alismatidae )
Order Alismatales ( Alismatales )
Family Hydrocharitaceae ( Hydrocharitaceae )
Genus Blyxa — Blyxa.
Hydrochemical parameters do not play a major role for them. They can successfully live in water with pH 4.5-7.0, at T 15-29°C. In addition to B. japonica, which has long been known in cultivation and is distributed in a vast region from Bengal to Japan, amateur aquariums also host Blyxa echinosperma from southern and southeastern Asia, with Blyxa octandra, Blyxa leiosperma, and Blyxa aubertii also growing here.
Differences between certain species appear only in the shape and size of flowers and seeds. All species of the genus have only a weakly developed rhizome and very fragile, thin, and brittle leaves, which greatly complicates their replanting and transportation. These delicate plants need to be planted in open areas of the aquarium separately, cannot tolerate shading by other plants, require very clean water, and suffer from algae overgrowth under bright lighting.
Aubert’s Blyxa — Blyxa aubertii.
“1” (Eng. Roundfruit Blyxa, Bamboo Plant). Madagascar, Australia, southeastern and central Asia, in marshy areas, small lakes, and slow-flowing streams. Has very fragile leaves. An elegant, highly picturesque herbaceous plant: each tuft is an annual plant, and if not propagated regularly (achieved, among other things, by dividing the rhizome), the population quickly degenerates.
Leaves are gathered in a rosette on a short, upright rhizome, becoming progressively slenderer toward the apex and tapering into thin tips. Has 20-50 basal stalkless green or yellowish-green leaves. The leaf blade is sessile, linear with an elongated-tapering apex, soft, brittle, light green in color, up to 6 cm long and 0.6 cm wide. The central vein is distinct, lateral veins are parallel. Leaves are ribbon-like, edges slightly serrate. Grows up to 15-40 cm.
“2” Usually kept in aquariums with clean water and a bottom composed of well-washed silicate sand. Like all representatives of the genus, this is an undemanding plant that prefers a slightly acidic active water reaction. Although it develops best in soft and acidic water, satisfactory cultivation is also achieved in acidic water of medium hardness. Nutrient substrate promotes the development of robust specimens. The substrate should be fine, as only in this case strong and beautiful tufts develop.
For optimal plant development, a bright, unobstructed spot is necessary. Plants placed in a well-lit location at pH around 6.0 and dH 0-10° develop best and fastest. The optimal water temperature is 20-22°C, but it also tolerates lower (down to 15°C) and higher (26-28°C) temperatures. Necessary conditions include bright lighting, a long daylight period (at least 10 hours), and a nutrient-rich substrate. Under moderate lighting, leaves are dark green, especially if nitrate levels are high. Dim lighting and excessive shading lead to the detachment of individual leaves. Under bright lighting, the plant will have dark red leaves. A red tint to the leaves may increase with iron supplements. The plant responds positively to both root and liquid fertilization.
“5” Adapts quickly to new conditions, does not require complex care. Dense thickets of rosettes of this blyxa with numerous ribbon-like leaves reaching a height of 30-40 cm look great in the middle or background. Snails, which are very fond of nibbling on the delicate leaves of the blyxa, should not be kept in the same aquarium with these plants. Due to the brittleness of the leaves, frequent replanting of the plant should be avoided. Planting density: 1 plant per 20 cm2.
“6” In the aquarium, Blyxa aubertii is a short-lived plant, so its timely propagation must be ensured. Vegetative propagation occurs rather slowly. Well-developed plants form root offshoots, which can be used for propagation by dividing them into 2-4 parts. Division of an undeveloped rhizome is unacceptable, as this not only makes it impossible to obtain full-fledged young plants, but also carries a high probability of death.
Japanese Blyxa — Blyxa japonica.
“1” Synonym: Hydrilla japonica. Distributed in water bodies and swampy places of China, Korea, Japan, Thailand, Indochina. A rather ornamental aquarium plant suitable for use in both compact and spacious containers. This plant features dense, even leaves. Highly variable: the shape of the tuft, its height, and leaf coloration largely depend on growing conditions.
Leaves are linear, narrow, and long, gathered in a rosette, very soft, 0.7 cm wide. Alternate, sessile, narrow leaves with sharp tips extend from the stem. Coloration is variable and depends on maintenance conditions. Leaf color ranges from bright green to yellow-olive, and under abundant light, they become reddish with a golden tint. Bush height ranges from 7 to 15 cm. The stem and leaves are very fragile. Not recommended for aquariums housing herbivorous fish.
“2” Prefers soft or medium-hardness water dH 4-10°, pH 5.5-7.5, water temperature 23-27°C. In harder water, it degrades and dies. Once the general hardness reaches 10 degrees, the roots of the blyxa dissolve, and it floats to the surface. The water must be clean; the appearance of turbidity noticeably worsens growth. The plant requires CO2 supply. It loves fairly strong lighting, under which it grows very quickly, turning into lush and bright bushes. Under conditions of light deficiency, carbon dioxide, and mineral starvation, blyxa growth slows down, apical growth stops, and lower leaves die off, exposing the stem. Japanese blyxas grown under high lighting are compact and squat. The height of these tufts does not exceed 6-7 cm — true dwarves.
Leaf coloration varies depending on lighting regime, CO2, and other habitat conditions. Under these conditions, the plants are compact, and the leaves turn golden with a reddish tint. Blyxas that do not receive enough light stretch upward, reaching a height of 10-15 cm, but unlike most other stem aquarium plants, they do not lose their decorative appeal and retain a beautiful green color. By placing blyxa in pots or dishes hidden by other interior details (e.g., clumps of Java moss), positioning it at different levels of the tank, and manipulating light sources, you can achieve tufts of various sizes with different leaf colors. For example, an unrepeatable effect is achieved by planting Japanese blyxa in a “path” from bottom to top.
“4” The root system is well developed. It roots with difficulty. Recommended practices include regular water changes with fresh water of similar parameters, applying root fertilizers (clay, sapropel) and liquid fertilizers. Blyxa loves nutrient-rich soil. When planting in aquarium substrate, it is extremely desirable to provide root fertilization. Adding macro- and micronutrients in the form of fertilizers strongly stimulates blyxa growth. However, in a tank with a large number of fish, natural silting may be sufficient for full development. Blyxas also react positively to soluble fertilizers.
“5” Unlike Blyxa aubertii, Japanese blyxa forms a beautiful stem rather than a rosette, which can be densely covered with leaves. In the aquarium, it forms squat, compact thickets suitable for decorating both the foreground and flanking areas of a home water body. The number of narrow (0.5-1.5 cm) leaves, 15-25 cm in long, can reach up to 100 on a single plant. A single plant is planted in the foreground, and relief groves formed by compact planting at different levels look very decorative.
To achieve the most decorative effect, it is best to plant in groups. It looks very good when planted in multi-level terraces. It is advisable to plant in the foreground and middle ground of the aquarium, where it forms dense light-green thickets. The plant can also be attached to driftwood or other aquarium interior items. Growth rate is moderate. Maintenance conditions are very difficult. When cultivated under good conditions, lateral offshoots emerge from the main stem. Their number is determined by the condition of the plant. Planting density: 2-3 plants per 20 cm2.
“6” Propagated by dividing lateral shoots extending from the rhizome. Over time, aerial roots develop at the base of these offshoots. A young stem with several roots can be safely separated from the parent plant and grown as a cutting. Young plants root poorly.
Identification: Genus Blyxa — Blyxa aubertii, japonica.
Spiny-seed Blyxa — Blyxa echinosperma.
“1” Distributed in swampy places of Sri Lanka, India, China, Japan, tropical Australia. A very original annual plant with long, narrow, sedge-like leaves of dark green with a brown tint. The stem is straight and short. A tuft of basal, narrow, and linear pale-green leaves extends from it. In an aquarium, it reaches a height of 40-50 cm. Grows evenly throughout the year.
“2” A tropical aquarium with a water temperature of no less than 24°C is best suited for this plant. The water in the aquarium should be clean, and up to 1/4 of the aquarium volume should be replaced regularly. Lighting should be quite strong and diffused. With a lack of light, the leaves lose their beautiful brown color and become pale.
“4” The well-developed root system consists of separate tufts of fibrous roots. The substrate must be nutrient-rich. Adding rich clay to the substrate improves plant growth. Nutrient soil promotes the development of robust specimens. A lump of clay should be placed under the roots in new substrate. Considering the size of the plant and the length of the roots, the substrate must be laid in a layer of at least 5-7 cm.
“5” The plant is suitable for keeping in a large container. It should be placed in the middle or background of the aquarium. Freely planted in the center of the aquarium, unshaded by taller plants, blyxa looks very beautiful. Restless and herbivorous fish should not be introduced because they will nibble on the delicate growth. Blyxa grows slowly.
“6” The plant propagates by runners in the substrate. Young plants develop in the immediate vicinity of the parent plant. Plantlets separated from the parent tuft root with difficulty.
Egeria densa, Egeria najas, Elodea canadensis.
Hydrocharis morsus-ranae, Limnobium laevigatum, spongia. 
