Danios

Hardy, continuously active, easy breeders, unfussy eaters, danios have the ideal qualities for a starter fish. Like barbs, they are extremely gregarious.

Danioaequipinnatus

Larger than its cousins, the giant danio is just as hardy and easy to

A DANIO FOR THE BEGINNER

Known, raised and bred in Europe since the early 1800s, the striped or zebra danio

(Brachydanio rerio) has given countless hobbyists their first real thrill of excitement. Twenty years or so ago, a veil form appeared, though, curiously, this fish has not given rise to other selective forms. Its hardiness and its readiness to spawn have been put to use by scientists to test the toxicity of certain substances. Recently they managed to produce a line of clones: genetically identical fish, and therefore with the same reactions to a given phenomenon, thus eradicating the influence of genetic variability on experiments. Size: 5-6 cm.

SPAWNING THE ZEBRA DANIO

You can breed the zebra danio in a tank without substrate using a mixture of new water with some taken from the parents' aquarium. The hardness level must be low, pH neutral, and the optimum temperature is around 26-27°C. To prevent the parent fish devouring the eggs, which they will do with gusto, keep the depth of water between 10 and 15 cm. The eggs will then sink quickly: a layer of marbles prepositioned on the bed will provide safe lodging places. Alternatively, suspend a layer of fine netting halfway down, allowing the eggs through but not the parent fish. For a set-up like this, use two males to one female, choosing a female with a plump belly, indicating that she is ripe. After laying - which seems to be stimulated by the first rays of the morning sun - remove the parent fish. Incubation of the eggs (up to 200 or 300) lasts 2-3 days, with the fry swimming between the 6th and 7th days. It is vital to feed them small, live prey - infusoria or rotifers if you can get them.

• Brachydanio frankei

This species, which resembles a tiny trout, appears not to exist in the wild, possibly deriving from isolated laboratory stock. The fish currently sold commercially originate from localized breeding centers in South-East Asia. The leopard danio, as it is commonly known, lives in shoals near the surface and acclimatizes easily. A veil form exists, with markedly elongated fins. Size: 5-6 cm.

Brachydanio albolineatus

The pearl danio is a shoal-swimming, voracious feeder. It can survive temperatures below 20°C. Size: 6 cm. •

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