What are Zebra Danios?
The name Zebra Danio, or Zebrafish, describes the species “Danio rerio”, which is a small freshwater fish, part of the minnow family, in the order Cypriniformes.
They are characterised as typical streamlined river fish, teal blue in colour, and have distinct bright pale stripes along their bodies, giving them the appearance of zebra stripes, which gives them their name.
Where are Zebra Danios from?
Danios are very successful fish, and are found across a wide range of freshwater river basins all around South Asia.
They are found within silty, flowing rivers, stagnant pools, scrapes and marshes within parts of India, Nepal, Pakistan and a few other locations.
The fish you find at your local fish store however, have likely been captive bred, as these fish are easy to reproduce in a farm setting, or in the home aquarium.
Do Zebra Danios need a heater?
Unless you are keeping your fish outside or in a shed, no you will not need a heater to keep Danios.
Danios are temperate fish, and do not always need to be kept at tropical temperatures if they are to do well.
This is what makes Danios an alluring choice for beginner aquarists, as you do not need to worry about purchasing a heater for your tank.
Can Zebra Danios live in a tropical aquarium?
Yes, it is possible to keep Danios in a tropical tank, although it is best to keep them at low end temperatures, around 24C – 26C (75F – 79F).
Higher temperatures tend to cause increased activity and aggression levels in Danios, so unless you want your fish to become somewhat fin nippy and have a very fast metabolism, then it is best to keep them cool and comfortable.
They will also tend to live longer when kept cooler.
Can Zebra Danios live in an outdoor pond?
During late spring and summer, when the weather is stable, it is entirely possible to keep Danios outside in a pond.
However, during the colder parts of the year, in autumn and winter, it is advised to take the fish indoors, or to install a heater and insulate the pond fully, as your Danios may begin to struggle at temperatures below 14C / 57F.
If you live in a hot climate, then you may be able to keep your fish outdoors all year, but be careful as to not introduce them to a natural waterway or pond, as they could damage the local ecosystem as an invasive species.
How large do Zebra Danios grow?
Zebra Danios stay fairly small, reaching average sizes of around 1 to 2 inches in length, with most achieving spawning size at around 2cm, and being fully grown by their second year.
This is not to be confused with the Giant Danio, which is related, but is a different species that grows much larger.
What size tank do Zebra Danios need?
Despite their small size, we always recommend keeping Danios in larger aquariums, typically tanks which are over 2ft in length.
This is because although they are small, they are very active fish, and need plenty of open space to swim around in.
Danios are also highly social fish, and need the extra room so that a good number of them can be housed within the same space.
While they can be kept in smaller tanks on occasion, ideally we wouldn’t recommend anything smaller than 15 gallons if you want your fish to really thrive.
Water parameters for Zebra Danios
| pH | 6.5 – 7.5 |
| Hardness | Low – Moderate KH and GH |
| Temperature | 16C – 28C (61F – 82F) |
| Ammonia (NH3) | 0 ppm |
| Nitrite (NO2) | 0 ppm |
| Nitrate | <5 ppm |
What to feed Zebra Danios
Zebra Danios are true omnivores, and will eat almost anything, from frozen Brine Shrimp, Daphnia and Bloodworms, to flakes, to algae wafers, to boiled soft fruit or veg.
The best thing you can offer them is variety, providing a good mix of foods is key to success when keeping Danios, they can live long and healthy lives if given fresh foods as well as a mix of dry flakes and pellets.
Can Zebra Danios live with Goldfish?
If the circumstances allow it, you may keep Zebra Danios with Goldfish, but there are a few factors to consider before you house them together.
First off, is the size of the Goldfish, although they may seem peaceful and placid, Goldfish are opportunists, and if a smaller fish looks as though it could fit in their mouths, they can and will eat it.
Keeping Danios with large adult Goldfish is generally a poor decision for this reason, and although they are quick and nimble, at some point you will find that your Zebra Danios may begin to go missing one after another.
Another thing to consider is the breed and shape of the Goldfish.
Danios are hyperactive, and will always get to food first, so it is important that you avoid housing them with Goldfish that have swimming difficulties.
Certain breeds like Ranchus, Orandas or Black Moors have trouble when it comes to feeding competition as they are often encumbered by their extremities and unusual body proportions.
Their long finnage also makes them an easy target for fin nipping, so fancy breeds are best avoided.
They can be kept with young Common Goldfish, small in size, but as they grow larger they will become a threat to your Danios.
So Zebra Danios can be kept with Goldfish, but ideally only for a limited time.
Best tankmates for Zebra Danios
When it comes to selecting the best tankmates for Danios, we need to look for fish that are similar in lifestyle.
Danios are peaceful fish by nature, they are not inherently aggressive fish, but they can become highly boisterous and irritable at times, especially at warmer temperatures.
You need to look for fish that are similar in behaviour and physique, fish which are streamlined and just as boisterous as Danios.
Tankmates that do not do well with Danios are fish like Bettas, Guppies and Fancy Goldfish, as they are poor swimmers, with long attractive finnage which is a target for fin nipping.
They do best with fish that require similar water conditions, have no issues when it comes to feeding, and are not easy targets for bullying.
Corydoras paleatus
Paleatus Cories, sometimes called “Salt and Pepper Cories” depending on where you live, do well with Danios, they are armoured bottom feeders, living their lives at the lower end of the tank, sifting the sand for scraps of food.
They are never usually a target for fin nipping due to their armoured scales and barbed fins, they are peaceful, good swimmers, and enjoy the oxygen rich river setting that Danios prefer.
They are also able to go cooler, and can be kept at room temperature, perfect for that sub tropical community setup.
Rosy Barbs
Rosy Barbs work great with Danios because they have the same energetic nature, they prefer similar water parameters, have a similar diet, and are similar in size / body shape.
Rosy Barbs are also able to live within the same temperature range that Zebra Danios can, making an ideal pairing within a temperate community tank.
Florida Flagfish
Flagfish go well with Danios as they can hold their own, enjoy similar water parameters and are easy to feed.
Flagfish can be quite nippy at times, so pair well with a fish that can easily avoid being picked on, just be sure to provide plenty of space and cover.
How to sex Zebra Danios
Danios are not easy to sex as both male and female look very similar at first glance.
However, in sexually mature fish, it is possible to notice subtle differences that can help you identify them easier.
Typically, female Danios are much more round and plum around the sides, with males being more slim and streamlined, the best way to identify this is to observe the fish from above.
With this thicker build, females also possess a small protruding area around their anus, from where the eggs are released, however, it takes a well trained eye to notice this subtle difference between the sexes.
In short, these fish are difficult to sex but not impossible.
If you are acquiring fish from your local store to breed, it is recommended to get a group of them to maximise the chances that you obtain a mixed sex school.
How to breed Zebra Danios
Zebra Danios are very easy to breed, and are a great starting species if you want to get into breeding aquarium fish.
They are egg scatterers, and breed like most cyprinids, by dispersing eggs and sperm externally into the water in large congregations.
To successfully breed Zebra Danios usually requires two aquariums, one to house the parents in, and a second to raise the eggs and fry in, until they are old enough to be moved in with their parents.
Danios are cannibalistic, and will eat their own eggs and young if they manage to spot them, so if you want the maximum survival rate, you need to be able to separate the parents from their offspring.
The easiest way to do this is by setting up a secondary breeding tank, that is filled with moss, pebbles or spawning mops for the parents to drop their eggs into.
The tank should be cycled and should be gradually heated over a period of days to 28C / 82F.
With this, the fish should be fed extra high quality foods, and should receive regular water changes to induce spawning.
After the parents spawn, they are to be removed, and the eggs should then be raised on their own.
Danio fry are fairly easy to raise, and will take newly hatched Brine Shrimp, White Worms, Infusoria and crushed flake food.
After around 3 months, they will reach a size where they can be placed back in the tank with their parents.