These hardy fish are most often used to cycle a new aquarium, as they are more tolerant of a wide range of water conditions. Danios and Minnows are also used in aquariums to help bring out the more reclusive species that tend to hide among the décor in the well-planted or highly decorated community aquarium. Found predominately in Malaysia, Sumatra, China, and India, most species are farm raised in both the Far East and the U.S. Danios and Minnows require plenty of swimming room and a tight fitting lid, as they are prone to leaping out of the aquarium when startled.

The Danio genus comprises many of the species of Danionins familiar to aquarists. The common name "danio" is used for members of the genera Danio as well as Devario.

Taxonomy

The name Danio comes from the Bengali name dhani, meaning "of the rice field". The species Danio rerio was first described in the early 1800's by Francis Hamilton, a surgeon working for the British East India Company. About a century later, (1916) the genus was split; Danio being composed of the larger species and the new Brachydanio being composed of the smaller species, such as D. rerio.[1] However, in 1991 the two genera were recombined; most larger species that were formerly within the Danio genus such as the giant danio have now been reclassified into the Devario genus. Also, Brachydanio now a junior synonym of Danio.[

Characteristics

They are native to the fresh water rivers and streams of southeast Asia, but many species are brightly colored, and are available as aquarium fish worldwide. A number of the species have only been recently discovered, in remote inland areas of Myanmar and do not yet have scientific names.

They have two pairs of long barbels and are generally characterised by horizontal stripes (with the exception of the glowlight danio, panther danio and black barred danio which have vertical bars). They range from 4 cm/ 1.75 in) to 15 cm/ 6 in) in length. They generally do not live for more than two to three years and are probably annual fish in the wild.

In the wild, these fish consume various small aquatic insects, crustaceans, worms as well as in the case of fry, plankton.

In the aquarium

The care of members of the genus Danio are rather similar and easily generalized. They are easy to keep.

All of these fish are primarily surface feeders. They are omnivorous in the aquarium and will accept a wide variety of foods, though flake food is appropriate. Living in aquaria, live/frozen flaked foods are suitable, especially brine shrimp and sinking tablets. Danios are voracious eaters; be careful timid feeders do not starve in community tanks with danios. When conditioning Danios for breeding, it's advisable to feed them plenty of fresh foods.

Although boisterous and liable to chase each other and other fish, they are good community fish and will not generally attack each other or other fish, although they occasionally nip fins, more by accident than design and will, like most fish, eat eggs and any fish small enough to fit into their mouths.

They are best kept in a tank long enough for their active swimming, preferably with a current from a power filter (or at least airstone) as they often live in fast flowing streams in the wild. Generally this also results in them being sub tropical with cooler temperatures. They are good jumpers and a tight fitting lid is recommended

Schooling fish, they prefer to be in groups of six or more. Danios prefer water with a 6.0–8.0 pH, a water hardness of up to 5.0–19.0 dGH,a carbon hardness of 8 to 12 KH, and a temperature range of 68–80 °F (18–24 °C), the lower end of the temperature range is ideal.

Blue Danio

Family: Cyprinidae
Range: India
Size: Up to 2 inches
Diet: Omnivore
Tank Set-up: Freshwater: Plants, rocks
Tank Conditions: 73-77°F; pH 6.5-7.0; dH 8-12
Minimum Tank Capacity: 10 gallons
Light: Medium
Temperament: Peaceful
Swimming Level: No specific level
Care Level: Moderate
Reproduction: Egg Layer

The Blue Danio, sometimes referred to as the Turquoise Danio, is a slender-bodied, active, schooling fish ideal for the community aquarium.

Native to streams and pools, the Blue Danio does well with other Brachydanio species and other peaceful fish of similar size. Kept with others in a school, this fish will be very active. The Blue Danio prefers a planted aquarium with plenty of swimming space available.

Brachydanio kerri scatters its eggs in shallow water over a substrate of coarse gravel. After hatching, usually within 36 hours after spawning, the fry should be fed fine pieces of live foods. Sunlight may trigger spawning.

The Blue Danio is an omnivore and should be fed a diet of flake foods with plenty of vegetable matter, as well as freeze-dried bloodworms and tubifex.

Giant Danio

Family: Cyprinidae
Range: India
Size: Up to 4 inches
Diet: Omnivore
Tank Set-up: Freshwater: Plants, rocks, driftwood
Tank Conditions: 72-75°F; pH 6.0-7.0; dH 8-12
Minimum Tank Capacity: 30 gallons
Light: Medium
Temperament: Peaceful
Swimming Level: No specific level
Care Level: Easy
Reproduction: Egg Layer

The Giant Danio is an excellent fish for the larger community aquarium. A blue-green background on the fish is intensified by its gold spots and lines.

Danio aequipinnatus is a very active fish requiring a large community aquarium with plenty of swimming room. A hood should be installed on the aquarium housing this fish, as it likes to jump. Giant Danios should be kept in a group consisting of 5 or more fish.

An egg layer, the Giant Danio is stimulated to spawn by sunlight. After roughly 300 eggs are produced, hatching occurs within 36 hours. Fry should be fed fine pieces of live foods.

The Giant Danio is an omnivore and should be fed a diet of flake foods with plenty of vegetable matter, as well as freeze-dried bloodworms and tubifex.

Zebra Danio

Family: Cyprinidae
Range: India
Size: Up to 3 inches
Diet: Omnivore
Tank Set-up: Freshwater: Plants, rocks
Tank Conditions: 64-75°F; pH 6.5-7.0; dH 8-12
Minimum Tank Capacity: 10 gallons
Light: Medium
Temperament: Peaceful
Swimming Level: No specific level
Care Level: Easy
Reproduction: Egg Layer

The Zebra Danio is a long-time favorite among freshwater aquarists. Kept in groups, this active community fish will make a great addition to the aquarium. This fish is silver or gold with bright blue/purple lines.

Danio rerio does best in a planted community aquarium with plenty of space to swim. This fish gets along with other Danio species as well as other peaceful fish of the same size.

The Zebra Danio male generally spawns with and remains loyal to one female. A breeding pair should be placed in a breeding aquarium with fine-leaved plants for them to spawn over. Roughly 300-400 eggs are produced, and hatching occurs within two days. The fry should be fed small pieces of live foods such as newly hatched brine shrimp.