Aquarium fish: Pearl danio (Brachydanio albolineata)
Size: 5 – 6 cm
Water temperature: 16-25 ° C
Aquarium volume: 81 l
Pearl danio (Brachydanio albolineata ) – a species of aquarium fish from the carp family. Commonly called the mother-of-pearl, and in Poland, the rainbow-zebra. The colloquial nomenclature refers to the pearly shine of the body. Often underestimated and overlooked by many aquarists. In aquarium stores, kept in bright and unfinished tanks, it seems unattractive.
Healthy individuals, in good condition, kept in appropriate conditions, often show a full range of various shimmering colors.
The species is widely distributed. It is found in areas of Myanmar, Thailand, Laos, Cambodia, Vietnam, Malaysia and Sumatra, in major river basins including the Mekong, Caho Phraya, Mae Klong, Irrawaddy and Salween, and many smaller tributaries. It was described on the basis of a specimen from the “Tenasserim Province”, which could refer to one of five or more modern states in Burma, most likely a former division in the south of the country, now known as the Tanintharya region. Later authors usually used the description of a specimen from Sumatra – Weber and de Beaufort (1916).
Depending on the location, the fish show variations in color, pattern and morphology, and it is possible that if detailed research is performed, the species may turn out to be a complex of many closely related fish. Currently, wild specimens are rarely found commercially, with the vast majority being produced commercially in Southeast Asia or Eastern Europe. It lives in a variety of aquatic environments, from well-oxygenated, clean, rocky streams that flow through forested areas to standing water bodies such as ponds, ditches, and rice fields.
Characteristics and disposition
Most individuals have an iridescent purple or pink body, an orange-neon stripe that runs roughly one third of the body’s length to the caudal fin, yellow or neon-orange eyes, olive marks on the body, and subtle yellow markings on the transparent fins. The scales glow metallic green to blue.
The muzzle is pointing upwards, with two pairs of whiskers in its vicinity. Sexually mature females are slightly larger, rounder and less colorful than the smaller, slender males. The differences are especially noticeable during the spawning season, when males become intensely colored and females fill with eggs. Sociable, vigorous and mobile fish. In nature, they swim in shoals, so in an aquarium they should be kept in groups of at least 8-10 individuals.
In this amount, they are less nervous, look nicer and present more interesting natural behavior, e.g. when intensely colored males compete for the favor of females.
Nutrition and feeding
Nutrition studies in wild specimens have shown that this species is predominantly insectivorous, so it feeds on various aquatic and terrestrial insects and their larvae. There were also small amounts of algae, other plant material and organic debris that could have come from the contents of the eaten insects in the stomach contents. In the aquarium, they are not picky and eat most food.
The basis of the diet can be good-quality dry foods, which should be supplemented with small frozen and live foods, such as water, daphnia or artemia. Due to their high spontaneity, you should remember to cover the aquarium after feeding, as they can easily jump out of it. Although they spend most of their time in the upper half of the reservoir, close to the surface, they also eat food from the depths and the bottom.
They look particularly impressive in aquariums with a lot of plants and a dark substrate. In bright, poor environments, their colors may be faded.
They will do best in an aquarium designed like a flowing river, with various sizes of gravel ground, a few larger smooth stones and lush vegetation. To ensure proper water movement, additional circulators can be used, but at the same time it should not be too strong. In nature, smaller species of zebrafish inhabit quieter stretches of streams and coastal zones. Roots, branches and durable aquatic plants, such as Mikrozorium, Bolbitis or Anubias, which can grow attached to objects, can also be used as decoration. The aquarium must be well covered, as Danio are excellent jumpers and can jump out even through a surprisingly narrow gap.
When choosing an aquarium, the length is more important than the height. For a group of 6-8 individuals, about 80 l tank is enough. The optimal water temperature should be 20-25 ° C. Higher temperatures may be tolerated, but for a short period of time. A very mild-mannered species, with no special requirements to water chemistry, ideal for social tanks.
It can be combined with many popular fish, including small carp, tetras, beautiful fish, rainbow fish, catfish, labyrinths and bots. When choosing co-residents, it is always recommended to carefully check the information on this matter in advance, and do not forget about its small size. In the biotope aquarium of the Mekong River, he may be in the company of representatives of the genus Acanthocobitis, Annamia, Balitora, Homaloptera, Nemacheilus, Schistura, Sewellia, Lepidocephalichthys, Pangio, Yasuhikotakia, Crossocheilus, Devario, Garra, Rasbora, Glossogichobius, and Rhinogorichobiusly and Rhinogoborichobius .
Like many other small cyprinids, Danios scatter their spawn and show no parental care. In well-kept, densely planted aquariums, fry can appear in small numbers without the breeder’s intervention.
However, if we want more fry, a slightly more controlled approach is required. For this purpose, we need to set up a separate spawning aquarium, approx. 20-30 liters, half filled with water. It should be poorly lit. Alternatively, you can also use commercially available artificial grass mats or fill the aquarium in large part with small-leaved plants, e.g.
moss. Desirable conditions of water for reproduction are neutral to slightly acidic pH and temperature at the upper limit, i.e. 24-26 ° C. A small sponge filter can be used for filtration, and it should be positioned so that the flow is directed downwards along the entire length of the tank. We feed adult fish with live food more than usual.
When the females appear thicker (full of eggs), introduce one or two pairs into the spawning tank in the evening. Spawning can be triggered by adding a small amount of cooler water every few hours so that the tank is gradually filled. Spawning usually takes place in the morning of the next day, which is easiest to tell when looking at the female. If the fish shed its eggs, it will be visibly thinner. Adults eat their eggs, so after noticing the eggs, they should be separated.
Incubation is somewhat temperature dependent, but usually lasting 24 to 36 hours, cubs begin to swim freely a few days later. Initially, we give micro foods in liquid or powder until the fry are older enough to accept the Artemia larvae.