Zebra Danio (Danio rerio)

Common Name:

Zebra Danio.

Scientific Name:

Danio rerio.

Family:

Cyprinidae.

Distribution:

They can be found in six different nations in Southeast Asia: India, Bhutan, Pakistan, Bangladesh, Nepal, and Myanmar.

Size:

1.5-2inches (4-5cm).

Diet:

In the wild, they can be micropredators, they eat small crustaceans, insects, and little worms. They do eat vegetation, and the presence of fine-leaved plants may take care of their need for roughage. High-quality flake and pelletized foods will also contain the right mix of nutrients to keep these fish thriving. Like almost all other fishes, they will be quite happy with the addition of live foods to their diet. They are often used as mosquito control in temperate ponds but they should be brought in for the fall if such is the temperature routinely falls below 64 degrees Fahrenheit in the winter.

Water Temperature:

In the aquarium, they can regularly withstand temperatures between 64 and 79 degrees Fahrenheit. This can actually qualify them as coolwater fish in that they can easily handle room temperature.

Water Chemistry:

These can survive a range of water qualities. In the wild, they live in waters with pH between 6 and 8 and dH between 5 and 19. Almost any tap water (once dechlorinated and dechloraminated) will suffice for CBB D. rerio but acclimation processes should be used if your water's pH or hardness lie outside the given ranges or differ greatly from that in which they were kept at the LFS. They do best with planted tanks (filled with open swimming spaces).

Housing:

15 gallons for a group of six, a correspondingly larger amount for more.

Sexing:

In mature specimens, the males are much slimmer than the females. If comparing two wild-type D. rerio of opposite sexes, the background will be more golden on a male and a paler yellow on a female.

Breeding:

These are reputedly among the easiest egg-layers to breed, perhaps easier than the White Cloud Mountain Minnow (Tanichthys albonubes) and the Convict Cichlid (Archocentrus nigrofasciatus). Depending on your view, you may choose to use mated "pairs" or you may choose to condition all of them and merely pick a female and a male. Merely heating the water to a temperature in the mid to upper 70s Fahrenheit and oxygenating it somewhat will likely trigger a spawning response. (I believe that this simulates a rainy season and the unification of their stagnant pools to the rivers of the area.) Another aspect of breeding D. rerio which has multiple schools is the adornment of the spawning tank. Some recommend a heavily-planted display tank and just allowing the young to grow up along side their parents in single-species tanks. Or floating plants may be used in such a tank and then removed to a separate incubatory tank. Others recommend layering the bottom of the spawning tank with marbles so that, once-scattered, eggs will not take on the role of sustainence for the hungry parents. The fry can then grow unmolested in the rearing tank once the parents have been removed. Specially feeding the fry, if such is desired, will be most easily done with a culture of infusoria and fry foods intended for egg-laying fish.

Description:

Among the fish to have a large impact in the hobby, D. rerio is surprisingly only 2-1/4" long at a maximum. These are torpedo-shaped, streamlined little fishes that are built for speed. They have a yellow background upon which (usually five) horizontal royal blue stripes that span the length of the fish are placed. Their fins are correspondingly striped, but more brilliantly so. Interestingly enough, many aquarists do not recognize the feature which makes them a "barb" (according to Elson and Lucanus in The Barbs Aquarium); they have two pairs of barbels which are often overlooked.

Behaviour:

These are reputedly fin-nippers but only anecdotally so. They are boisterous, so they should not be kept with slow-moving, easily-annoyed and large-finned counterparts. They swim very quickly, and manifest a fright coloration that is very dull when their environment has been changed rapidly and in an unfavorable manner. They are quick to evade a predator, net, or something else that may scare them. Anyone who's ever kept a tank of these will confirm their prowess at evasion. They should be kept in a group of their own species as this will help to make them feel more comfortable. They really are social fish, so taking away the society of conspecifics is not recommended nor is it a "humane" way to keep them. They will occupy any of the levels of the aquarium, so plan their tanks accordingly.

Ease of keeping:

Excellent beginners fish, hardy, fun and colourful, makes an excellent addition to any planted peaceful aquarium.

Miscellaneous:

Though Brachydanio was once created to house these and several of the other shortened Danio;, this is now regarded as invalid. They have since been returned to their initial genus and will likely stay there as such is the widespread scientific opinion. As mentioned before, these fish make for excellent mosquito control in a small pond. They also evade predators better than some of the other common choices (Paradisefish and Goldfish). These are among some of the most-researched vertebrates and were, according to some accounts, the first vertebrate to have been cloned. Many American universities now have fish rooms devoted to the rearing (and squishing) of Zebra Danios for genetic studies. Their ease of breeding and genetic morphological variability are often cited by scientists as reasons to keep them handy in the lab. The TK-1, a now commercially-available phosphorescent fish, is a Zebra Danio that has been infused with cnidarian genes. There are albino and long-finned variants commercially available. Long-finned variants cannot compete for food with those that have the wild-type finnage. They also may have their fins nipped by other D. rerio specimens.

Photo Credit:

Photo 1 supplied courtesy and ^©Big J.
Photo 2 supplied courtesy and ^©Xinnix.