3 danio rerio and 2 tetra glofish

Zebra Danio Care Guide: Tank Setup, Mates, Illnesses, and Breeding

There are two things you need to know about the danios: 

  • They love to swim
  • They are social fish

Other than that, they are sturdy tropical fish that can survive in a variety of conditions. But they will thrive only in a shoal of six or more.

They need ample space to swim around. You will commonly see that they can live in a 10-gallon tank. That’s a rather small fish tank that could suit a single, lonely, sad danio.

But more on that in a bit.

Let’s get the other basics out of the way first.

Zebra Danio Basic Care: Water Parameters and Tank Size

Danios can live in a variety of conditions. I’ll share the complete range of temperature and water parameters plus the ideal conditions that will keep your fish happy and thriving.

Danio Water Parameters

 Danios need the following water parameters:

  • Temperature — 18-30°C or 64-84°F, with the ideal range being 23-27°C or 73-81°F.
  • Water pH — 6.5-7.5 pH range is ideal for danios. They like neutral waters but can tolerate up to 8.5 as well.
  • Water hardness —  6–18 dGH, again, wide range.
  • Water current — Medium flow will suit them well, but danios can live in fast-flowing or barely moving waters, too.

You can keep them with most tropical fish without any issues. There are a few species that are best avoided as danios can be semi-aggressive, especially toward fish with large fins or other fish of similar size to them.

But more on that in a bit.

First, tank setup for danios.

Tank Size and Setup for Danio Rerio

Now, all danios are avid, fast swimmers. They like to live in groups and chase each other around playfully (or a bit rudely).

A 40-liter or 10-gallon tank is the standard recommendation you will see, but I’d strongly recommend at least double that. A long, shallow tank is way better than a deeper aquarium. Danios swim in straight lines most of the time and will appreciate all the space they can get.

  • Tank size — At least 20-gallon, long tank, so they can swim around freely. 10-gallon could work for the smallest danio species (probably the spotted danio tinwini takes the honors in this category), but the bigger the tank the better.
  • Tank shape Definitely opt for a longer tank if you plan to keep danio. They love darting around in vertical lines.
  • Substrate — While danios move all around the tank, they dwell primarily at the upper tiers. Both sand and gravel work fine, as well as specialized soils.
  • Decorations — Plants, rocks, driftwood, and other decorations work fine. Danios don’t hide much (too hyperactive for that) but like to have floating vegetation or giant vallisneria that shelters them from above. They often sleep among stalky, long plants.
  • Light — Any aquarium light will do, really. Glofish danios will shine the brightest with a blue light.

There you have it, that’s the basic setup you need to keep danios.

Now, let’s find out more about these playful species.

Danio Rerio: Origin Story

Zebra danios (Danio Rerio is their Latin name) are small, vibrant, and highly active fish that can add a lively touch to your aquarium.

While zebra danios are the most well-known danio species, there are several other varieties, such as the Glofish danios, which have been genetically modified to fluoresce under certain lighting conditions.

Zebra danios originate from tropical and subtropical waters in Myanmar, India, Bhutan, Pakistan, Nepal, and Bangladesh. That’s a lot of space, with different climates throughout the year. The tropical heat can raise water temperature above 30°C/85°F, but in winter, in the higher places, it can drop below 15°C/60°F.

The same goes for the waters they danios inhabit. From slow-flowing swampy regions to bubbling streams, danio fish is well-adapted to anything.

No wonder they are crazy.

Zebra Danio Appearance

Zebra danios are small fish that rarely grow over 5-7cm/2in. Typically, they have silvery skin with deep blue stripes all along their bodies.

  • Size — 5-7cm/2in but there are varieties as small as 2cm/0.5in or as large as the giant danio that can reach over 10cm/5in.
  • Longevity — 3-5 years

Danios are a staple in the hobby and this has led to selective breeding. As a result, today we have Glofish danios that sport striking colors like orange, green, purple, and more.

Additionally, there are long-fin danios that are a sight to behold. Well-bred long-finners swim around just as quickly but the elongated fins add a touch of majestic elegance to their frantic nature.

Difference Between Male and Female Danios

Danios are relatively easy to tell apart. Once they reach maturity — about 3-4 months after spawning — the females are slightly larger and more rounded.

The male danio fish are torpedo-shaped, slim, and straight.

Zebra Danio Behavior

Danios are among the most hyperactive species you will find. They swim around almost all the time, chasing each other, and establishing social hierarchies.

Zebra danios are shoaling fish. Their playfulness often verges on aggressiveness, but that’s how danios behave — chasing around is their way of creating society.

You should keep at least six of them, but more doesn’t always mean better. Too few danios are likely to cause damage, as the attention of the strongest danio will fall too often upon the weakest member of the group. Conversely, putting too many danios in too tight a space will lead to aggressive behavior.

In general, danios are not aggressive, but they are mildly territorial, which could lead to conflict. A way to mitigate territorial disputes is to provide separation in the tank, be it through plants or hardscape.

Danios are known fin-nippers, so guppies and larger, slow fish could be targeted.

Zebra Danio Tankmates

Danio rerio with sufficient swimming space and company of its own kind will rarely bother other fish. Unless they have very tempting large fins, in which case the danios are likely to nibble.

I’ve also seen them playing with guppies, which can lead to damage. Guppies often are of similar size and danios treat them like other danios, playing aggressively. The guppies would rarely appreciate that, as their nature is lethargic and derpy, not hyperactive and pointy.

Great tank mates for zebra danios include:

  • Barbs
  • Tetras
  • Gouramis
  • Loaches
  • Swordtails
  • Catfish
  • Bottom-dwellers of all kinds
  • Snails
  • Most shrimp

Zebra Danio Diet

Danios are not picky eaters and readily accept a variety of foods.

Their diet should include:

  • High-quality flakes
  • Wafers
  • Veggies like cucumber or spinach
  • Daphnia
  • Live foods

Feed them small amounts 1-2 a day, ensuring they consume all the food within a few minutes to maintain water quality.

Treating them occasionally with mosquito larvae or blood worms will make their colors pop even more.

Breeding Danios — An Easy Way to Start Breeding Fish

Danios are prolific breeders that can lay over 400 eggs!

Of course, when perfecting your breeding technique, the results will likely be more moderat, but danios are an excellent choice for breeding egg-laying fish for the first time.

Here are the steps to follow if you wish to breed danios:

  1. Pair up a plumper, rounder female with a slim, elongated male. Two males and four females will give you a good chance to get fertilized eggs.
  2. Provide a high-protein diet to show the fish it is breeding time.
  3. Set up a separate breeding tank with a fine-leaved spawning mop.
  4. Danios are voracious egg-eaters. To stop them from eating their future offspring, you can cover the bottom of the tank with pebbles. Many eggs will fall through the cracks, becoming inaccessible for the always hungry parents. Alternatively, you can keep the fish in a plastic basket with mesh fine enough to allow the eggs to fall through (danio eggs are tiny) while restricting the parents.
  5. Keep the light medium-to-low.
  6. Keep the water temperature at 25°C or 76°F.
  7. When the eggs are laid, remove the parents immediately or watch them feast upon the unhatched fry.
  8. Once the eggs hatch, provide the fry with infusoria or finely crushed flakes until they are large enough to eat standard fish food. Boiled egg yolk diffused in water is another great option for newly hatched fry. Boil the egg, dissolve it thoroughly in water until all of its particles have melted away, and feed the fry 2-3 times a day. Use a syringe to sprinkle the nutritious “soup” around the tank.

The most crucial factors in succeeding are the food quality and the water temperature. Keeping a breeding tank clean, with ideal water parameters, shouldn’t be that difficult.

Common Danio Illnesses and Afflictions

While danios are generally hardy fish, they can still face some health issues. Here are a few common problems you might encounter and how to address them:

  1. Ich (white spot disease) — Ich is a common fish disease characterized by white spots on the fish’s body and fins. Quarantine infected fish immediately and treat them with an ich medication or salt. Raising the tank temperature slightly also accelerates the life cycle of the parasite, reducing its reproduction window, and making it more susceptible to treatment.
  2. Fin rot — Fin rot is a bacterial infection that can manifest as frayed or disintegrating fins. Improve water quality (check for ammonia), perform partial water changes, and administer antibiotics if necessary. Isolate infected fish in a hospital tank to prevent the spread of the disease.
  3. Swim bladder disorder — If a danio is having trouble maintaining its buoyancy and swims erratically or upside down, it may have a swim bladder issue. Ensure your fish are not overfed and vary the diet a bit, to see 
  4. Stress ailments — Stress can weaken a danio’s immune system, making it susceptible to diseases. Stress in itself is not a sickness but can lead to many diseases if you don’t recognize the symptoms on time. Maintain a stable environment, avoid sudden changes in water parameters, and provide ample hiding places to reduce stress.
  5. Aggression — Occasionally, danios can exhibit aggressive behavior, especially if their group is too small. Increasing their numbers or providing more hiding spots can alleviate aggression.

If their diet, social needs, and water conditions are met, you should have a stress-free experience with these quick swimmers.


The danio care guide is on the longish side, but this is because the species are fascinating, not because they are difficult to keep.

On the contrary, danios are very beginner-friendly fish that will liven up your aquarium with incessant movement and colors.

Provide them with adequate company and diet, maintain the water parameters intact and you will have them darting around happily for a good few years.

Why do scientists use zebra danios?

Danios and humans share many genetic characteristics, making the species nigh-ideal for scientific research. You’d be surprised how much the little unassuming danio contributes to the advancement of humanity.

Are zebra danios nano fish?

Danios can live in nano tanks. The smallest danios won’t feel too restricted in a small tank, but if you take one thing away from this danio care guide let it be this: they need room to swim.

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