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Zebra Danio – Danio rerio


Zebra Danio

Danios are amongst the most popular aquarium fishes. There are probably more than 30 distinct species of Danio from which the aquarist may choose and this includes a large number of visually stunning fishes that are bound to enhance any home aquarium.

Is the Zebra Danio a good community fish? The Zebra Danio should be considered to be an excellent community fish assuming that the community is one of small to medium-sized (1 to 5 inches) species, being that adults are around 2 inches long. The Zebra Danio is suitable for aquariums either with a significant water flow (like a stream) or for a normally-aerated aquarium. The Zebra Danio is an excellent choice for novice aquarists.

Key Facts

CategoryKey Facts
Common name(s)Zebra Danio – also known as:
Zebrafish
Striped Danio
Scientific nameDanio rerio
FamilyCyprinidae
Originate fromIndia, Pakistan, Bangladesh, Nepal and Bhutan in Asia
Care requiredEasy to care for and hugely popular
TemperamentPeaceful, shoaling fish
Colour & FormTorpedo-shaped with alternating blue/black and gold/silver stripes along its body and fins.
LifespanUp to 5 years
Adult size2 inches
DietOmnivorous – eat aquatic insect larvae in nature
Aquarium size24 inches in length or greater
Compatible withMost other Tetras, Barbs, Danios, Guppies and other livebearers, dwarf cichlids, smaller Gouramis, catfish and loaches that live in fairly neutral, soft water
Avoid keeping withLarge and/or aggressive species and species with long-finnage
BreedingEasy if you put the fish in the right environment.
Water temp64 – 75 Fahrenheit
Water pH6.5 to 7.0
Water hardness (dGH or dH)5 to 12 dGH

Origins of the Zebra Danio

Danios, as a “family” of fishes belonging to the biological family Cyprinidae and are found in nature in south and southeast Asia.

The Zebra Danio is found in India, Pakistan, Bangladesh, Nepal and Bhutan in Asia.

Characteristics of the Zebra Danio

The Zebra Danio is an impressive little fish. It has a torpedo-shaped body, and It will grow up to around 2 inches in the aquarium and live for up to five years. 

Zebra Danios prefer fairly soft, neutral water with a pH of 6.5 to 7.0 with a temperature range between 64 and 75 degrees Fahrenheit and up to 5 to 12 dGH. 

The Zebra Danio enjoys soft to medium, neutral water conditions so it will be comfortable with other species of similar size that prefer this type of water chemistry.

The female is generally larger,  deeper and wider bodied than the male and displays less intense color than the male in the body at spawning times. The male tends to be somewhat slimmer and its coloring is more intense in the body than the female.

The Zebra Danio enjoys constantly flowing water as well as still water so the aquarium needs to be set up in such a way that it has a current of water from one end to the other against which the Zebra Danio will constantly swim or the water can be relatively static. Clearly, in its natural habitat of river drainages that can have a water flow, The Zebra Danio is adapted to that environment.

That said, the Zebra Danio will live quite happily in an aquarium that does not have that constant flow of water but, to compensate for this, the Zebra Danio will be pretty constantly on the move.

The Zebra Danio can even be kept with goldfish, provided that the goldfish aren’t so large that the Zebra Danio may be eaten.

The coloring of the Zebra Danios such that it is comprised entirely of dark blue/black stripes and gold/silver stripes running the full length of the body and extending into the fins.

The Zebra Danio is a gentle fish, always on the go but at a relaxed sort of pace, so it is just fine putting it with other community species including slow-moving, unless they are significantly larger (in which case the larger may seek to eat the smaller fish). The Zebra Danio has a reputation for being a fin-nipper so it’s best to avoid putting them with long-finned species.

The Zebra Danio is a shoaling fish and should be kept as a group of at least six fish, though a shoal of, say, twenty or more fish is highly recommended. Since this is a small species, there is every reason to have a decent-sized shoal in a decent-sized aquarium to ensure that it has plenty of space in which to behave naturally, as it always does better in a larger shoal.

Having plenty of vegetation to break up lines of sight will also help to protect your Zebra Danios from predation but it is obviously advised that Zebra Danios are not kept with predatory species, as they are a very peaceful fish and may be seen as prey.

Overall, the fish is most attractive and most elegant.

It is fairly to distinguish the sex of adult Zebra Danios because the adult female is larger and a broader whilst the male tends towards being more streamlined and with more distinct coloring. The female is also fuller-bodied, especially when carrying eggs (gravid). 

The Zebra Danio seems to inhabit all areas of the aquarium. That said, it is a vigorous fish when breeding and will readily traverse the entire aquarium. It tends to feed in the middle and lower areas of its environment. They love brine shrimp, blood worms, tubifex worms and daphnia at least a couple of times each week but will accept freeze-dried food as well as flake food.

The Zebra Danio is, by nature, a shoaling fish and it is generally recommended to purchase at least six fish – preferably twelve to twenty-four fish, as their nature is to swim together like a shoal, against the flow of water and they will tend to thrive much better as a shoal. Zebra Danios are excellent community fish and are ideal for intermediate aquarists assuming that the soft, neutral and flowing water and appropriate breeding conditions required are provided and maintained.

It is generally advised that the minimum tank size for Zebra Danios should be one of at least 24 inches in length or more due to the constant flow of water required and the fact that they are very active swimmers indeed, which will enable a small shoal to move around freely. A smaller tank might be too restrictive and the fish will suffer as a result whilst a larger tank is always to be recommended.

There is a predominance of so-called “Nano tanks” available but, being old-fashioned, I prefer my fishes live in an environment which, at least, attempts to mimic nature, rather than living in what I would liken to a prison cell. The tank should be well-planted but with clear areas where the fish can swim freely. The water should have a decent amount of movement, as Danios enjoy swimming against a flow of water.

Zebra Danios are easy to sex when they are mature, where the female has a slightly fuller body when she is carrying eggs (gravid) than the male, which is likely to take on richer coloring and have orange edges to the ventral and anal fins.

The general rule for Danios is that by keeping six or more of the same species in an aquarium they will be fully aware of which is male and which is female and they will act accordingly when the time comes for breeding.

Zebra Danio – Videos

How do Zebra Danios breed?

Danios, in general, will scatter eggs by laying them over fine plants such as Cabomba, Fontanalis or Willow Moss or Java Moss.

Zebra Danios are like most other Danios in that they scatter their eggs. In respect of preparing a breeding tank for the Zebra Danio, it is generally recommended that the bottom is covered in marbles between which the eggs will naturally fall, safe from predation from its parents.

As the female Zebra Danio becomes ripe with eggs, the difference between the sexes may become more evident, as the body expands because it is carrying eggs. If you plan to attempt to breed Zebra Danios then it is recommended that you have a breeding tank prepared. Such a tank can be empty and should be tall and not more than filled to around nine-inches deep with water.

The water should have a reasonable current so the pump should not only be able to draw sufficient water to pump back as a current but should also include protection to ensure that the eggs do not get pulled through the pump.

The breeding pair will go through their mating ritual and the female releases some of her eggs and the male will fertilize them until up to 300 to 500 eggs, perhaps more, have been laid and fertilized.

Thereafter, the adults will take no further part in rearing their offspring and will eat the eggs, given the chance so it’s best to return them to the main tank.

It takes around two days for the eggs to hatch, depending on the water conditions and temperature and around a further two to three days or so for the yolk sacs to be depleted and the fry to become free-swimming.

In a well-planted aquarium, the Zebra Danio will often spawn in the community tank and at least some of the fittest fry will survive to adulthood.

Breeding tank for Zebra Danios

You should prepare a tank of around five gallons in size with mature, soft, neutral, flowing water. The water should have a low level of light and be no more than around nine-inches deep. It is recommended that the substrate consists of marbles through which the fry will fall. In essence, you are seeking to create a shallow stream.

By all means, include plants such as Java Moss or, perhaps, a sterile spawning mop to encourage breeding but take into account the fact that you will need to remove the adults once spawning is completed and you don’t want to injure either the fishes or the eggs.

Danios prefer to spawn where the water is flowing so a decent pump is required to synthesize that flow and the marbles will help to prevent the eggs from being drawn into the pump or consumed by the parents.

You may wish to introduce baby brine shrimp, mosquito larvae or bloodworm as an inducement to reproduction.

The male and female will swim amongst the plants (if any) and the female will lay laying around 300 to 500 eggs during a spawning. The male(s) will swim alongside or behind her and fertilize the eggs as they are laid. The eggs are not adhesive and will fall to the bottom of the tank. Once the female has laid all her eggs the adults should be removed from the breeding tank.

Reduce the water movement by turning down the pump – only regular aeration is now required. Keep the lights off (or very low) and the tank dark (of fairly dark)  because eggs and fry can be particularly sensitive to the light.

The eggs will hatch typically in two to three days depending on tank temperature and conditions and the fry will become free-swimming after around three days after hatching. Keep the tank unlit for the first week or so then gradually increase the lighting. Bear in mind that the eggs and fry of a fish as small as the Zebra Danio will be tiny indeed so you may need to use a magnifier “app” on your smartphone to see anything at all.

The newly hatched fry will feed firstly on their yolk sac but, once free-swimming, can be fed infusoria (particularly rotifers) and will also thrive on egg yolk during the first two to four weeks. It is worth mentioning that immediately after hatching, fry seem quite vigorous but will soon go into a resting state before they become free-swimming so please don’t mistake this initial stage as being free-swimming.

Once the fry are free-swimming and their yolk sacs are depleted, then add baby brine shrimp. Once the fry are sufficient in size not to be treated as a snack then they can be introduced into the community tank where they will join the existing shoal. Before moving the adolescent fish into the community tank ensure that you have balanced the water temperatures to mitigate the risk of White Spot or other diseases being triggered.

Unless you are breeding commercially, you may wish to consider moving the fry into the community tank sooner rather than later. It may seem harsh but the adult fish in the tank will deal with any fry that are unlikely to survive to adulthood in the wild and you are synthesizing, to the best of your ability, a wild environment. The fittest fry will probably survive whilst the rest will be dealt with by the community.

Should your Zebra Danios have a special diet for breeding?

Adult Zebra Danios don’t need any particular inducement to breed. That said, it has been suggested that adding baby brine shrimp, mosquito larva may encourage them, presumably because the addition of a new food may “fool” the fish into thinking that it is breeding time. From my own experience, I would always recommend keeping all of your fish in the best possible condition at all times, as this is good for the wellbeing of your fish.

Image courtesy of Wikimedia Creative Commons

Mike Wheeler

I started keeping freshwater tropical fish in 1972 and it has been something of a passion ever since. In this website, my aim is to build up an everyman's guide to help the everyday aquarist get the best from this inspiring and entertaining hobby.

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