‘Crypt melt’ is a phenomenon wherein the leaves of a crypt develop holes and then the plant appears to dissolve. It appears to be caused by changes in environmental conditions, including; water parameters, light intensity, CO2 levels and temperature. Additionally, moving crypts will almost always result in crypt melt.
Crypts don’t like to be moved, period. Purchasing crypts in pots will minimise the negative effects of transportation. In an established aquarium, crypts will usually recover from this ‘melting’. However, in a newly established aquarium, where the water parameters may be in flux, the chance of recovery is limited. As a result, crypts should be added several months after the tank is established. Once established, crypts are very hardy and long-lived plants.
Most crypts prefer warmer water and an enriched substrate. Crypts are slow growing plants, so the effect of lighting on growth rates is limited.
Keep in mind that most Crypts available in the hobby don’t like direct light. It should be diffused, perhaps going through a fine-leaved plant. Most of them won’t die under bright light, but they won’t grow, either, and leaf sizes could suffer.
Crypts prefer a temperature of between 25 and 28 degrees Celsius, a pH between 6.0 and 7.0 and moderately soft to moderately hard water.
While many sources may suggest that crypts tend to grow better in soft, sightly acid water, crypts are adaptable. As with most soft-water plants, they will grow well in harder water, due to higher nutrient levels. In my experience, crypts will not do well without nutrient rich substrates. High iron and potassium levels seem to be beneficial.
Low-wattage (25 or 50 watts) heating cables placed under the substrate improves their growth markedly, however, evidence indicates that this is true for most aquarium plants. I personally have never used heating cables, as I have been satisfied with the growth rates achieved without them.
Primarily they reproduce via runners, with daughter plants on the nodes, but they have to be very happy, in a well maintained, well established, tank, to do so. Otherwise, their growth can be maddeningly slow.
C. affinis: Originating Malaysia, C. affinis one of the easiest to keep. It reaches a height of 25 centimetres. Its crinkled leaves vary in shade and colour; usually they are a glossy light green, sometimes with a russet underside. C. affinis is one of the few crypts that can be considered a fast grower but growth will slow as the plant ages. Temperatures between 22 and 28 C are suitable.
C. albida: Originating in Thailand, C. albida reaches 25-30 centimetres. The leaves are spear-shaped and vary in colour from light green to red-brown. Very bright light can cause it to shorten it’s leaves. The Harlequin Rasbora (Trigonostigma heteromorpha) likes to spawn on the underside of this plant, as they do in nature.
C. balansae: Originating in Thailand, C. balansae has long, light green, and highly-indented leaves. The leaves can reach 40 centimetres but 30 centimetres is more usual. It reproduces by runners. It’s undemanding in terms of lighting but grows better in bright light. Temperatures between 25 and 28 C are suitable.
C. becketti: Originating in Sri Lanka, C. becketti is one of the most commonly available species. It reaches a height of 15 centimetres. It spreads by adventitious plantlets (small shoots from its stem), creating an attractive bush of a plant. The dark green leaves are oblong and on long stems. C. becketti is a sturdy plant, and many bottom-dwelling fish will use it for cover. Temperatures between 25 and 28 C are suitable.
C. walkeri: C. walkeri is commonly available. Single plants reproduce via shoots from its base, creating a dense forest where small fish may take refuge. C. walkeri reaches a height of 12 centimetres. It is undemanding in terms of lighting. Temperatures between 22 and 30 C are suitable.
C. cordata: Originating in Thailand, C. cordata grows to 40 centimetres or more and has large, ruffled, spear-shaped leaves. Leaves are olive green with red undertones. Due to its large size and mass, it can be a used as a centrepiece in mid-sized tanks. It reproduces both by plantlets from its base and runners. Not terribly easy to keep (but well worth the effort), cordata needs a heated, nutrient-rich substrate to do well. Temperatures between 22 and 28 C are suitable.
C. parva: Originating in Sri Lanka C. parva reaches a height of 5 centimetres. It requires bright light to do well, and when well established, will carpet your tank, giving a lawn effect. The plant is easy to care for if given a good substrate and very bright light. CO2 is necessary in order to achieve rapid carpeting. It prefers temperatures of 25 to 28 C.
C. wendtii: originating in Sri Lanka, C. wendtii is available in a dazzling number of leaf varieties. Leaves are normally dark to olive green, depending on the light. The underside of the leaves is usually an orange-brown colour. C. wendtii is one of the faster growing crypts, reaching 35 centimetres. It should be planted with 10-15 centimetres between plants. It spreads by shoots and runners. Light can be moderate to very bright.
C. undulata: Originating in India, C. undulata prefers hard water. The leaves are dark green with red stems. As it matures it can grow highly ruffled leaves more than 35 centimetres long, making it a dominant plant in most tanks. It needs bright, full-spectrum light. Temperatures between 22 and 28 C are suitable.
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