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 Blue Danio a good community fish? The Blue Danio should be considered to be an excellent community fish assuming that the community is one of small to medium-sized (1 to 4 inches) species, being that adults are around 2 inches long. The Blue Danio is suitable for novice aquarists as it gets on just fine with other similar-sized species.
|Common name(s)||Blue Danio – also known as:|
|Scientific name||Danio kerri|
|Originate from||Rakhine Yoma/Arakan mountains in Rakhine state, western Myanmar in southern Asia|
|Care required||Easy to care for and hugely popular|
|Temperament||Placid, shoaling fish|
|Colour & Form||Torpedo-shaped with almost clear finnage and turquoise/blue body with two orange lines along its flanks.|
|Lifespan||Up to 6 years|
|Adult size||2 inches|
|Diet||Omnivorous – eat aquatic insect larvae in nature|
|Aquarium size||24 inches in length or greater|
|Compatible with||Most other Tetras, Barbs, Danios, Guppies and other livebearers, dwarf cichlids, smaller Gouramis, catfish and loaches that live in fairly neutral, doft water|
|Avoid keeping with||Large and/or aggressive species and species with long-finnage|
|Breeding||Easy if you put the fish in the right environment.|
|Water temp||73 – 77 Fahrenheit|
|Water pH||6.0 to 7.0|
|Water hardness (dGH or dH)||1 to 15 dGH|
Origins of the Blue Danio
Danios, as a “family” of fishes belonging to the biological family Cyprinidae and are found in nature in south and southeast Asia.
The Blue Danio is found on the islands of Langkawi and Ko Yao Yai in Malaysia in Asia.
Characteristics of the Blue Danio
As you can see, the Blue Danio is an impressive little fish. It has a (slightly deep) torpedo-shaped body, and It will grow to up to almost 2 inches in the aquarium and lives for up to six years but generally lives for between two and four years.
Blue Danios prefer fairly soft, neutral water with a pH of 6.0 to 7.0 with a temperature range between 73 and 77 degrees Fahrenheit and up to 15 dGH.
The Blue 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 and hardier with a deeper body than the male and displays more of a blue color. The male tends to be somewhat slimmer and its coloring is more yellow than the female.
A well-planted aquarium with open space in which the Blue Danio can swim freely is preferred together with a decent flow of water.
The Blue Danio is a busy fish, always on the go, so it is best to avoid putting it with overly-static or long-finned species, especially if the latter are significantly smaller and/or particularly timid.
The Blue 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 Blue Danios from predation but it is obviously advised that Blue Danios are not kept with predatory species, as they are a very peaceful fish and may be seen as prey.
The body of the Blue Danio in good condition has a striking, turquoise/blue body with a pair of orange lines, the top one running along the center-line of the fish from behind the gill plate to the tip of the caudal peduncle and the second being slightly curved around the belly and running beneath the first, again to the caudal peduncle. The male can become deeply colored during spawning.
The fins are generally unremarkable being that they are more-or-less clear (hyaline).
Overall, the fish is attractive and most elegant.
It is fairly to distinguish the sex of adult Blue Danios because the adult female is larger and a richer blue whilst the male tends towards being yellowish. The female is also fuller-bodied, especially when carrying eggs (gravid). The male also tends to be slightly smaller and slimmer in profile.
The Blue Danio tends to inhabit the middle and lower 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 and, being quite a tiny fish will prefer small (preferably live) food. 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 Blue 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 and they will tend to thrive much better as a shoal. Blue Danios are excellent, tiny community fish and are ideal for novice aquarists assuming that the soft, neutral water and appropriate breeding conditions required are provided and maintained.
It is generally advised that the minimum tank size for Blue Danios should be one of at least 24 inches in length or more due to the shoaling nature of the species 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.
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 gentle movement, as Danios enjoy swimming against a gentle flow of water.
Blue 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.
Blue Danio – Videos
How do Blue Danios breed?
Danios, in general, will scatter eggs by laying them over fine plants such as Cabomba, Fontanalis or Willow Moss or Java Moss.
Blue Danios are like most other Danios in that they scatter their eggs. In respect of preparing a breeding tank for the Blue 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 Blue 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 Blue 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 release some of her eggs and the male will fertilize them until up to 400 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 between three to seven days for the eggs to hatch, depending on the water conditions and temperature and around a further twenty-four hours or so for the yolk sacs to be depleted and the fry to become free-swimming.
In a well-planted aquarium, the Blue Danio will often spawn in the community tank and at least some of the fittest fry will survive to adulthood.
Breeding tank for Blue Danios
You should prepare a tank of around five gallons in size with mature, soft, neutral 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.
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 do 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 400 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 a day or two depending on tank temperature and conditions and the fry will become free-swimming after around five 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 Blue 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 Blue Danios have a special diet for breeding?
Adult Blue 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.