The swell guide to danios - Help Guides - Swell UK

If you've never kept aquarium fish before then the best fish you can start with are danios.

Danios are small, very active, popular freshwater fish which are known for being incredibly hardy and their ease of keeping. They look like small minnows and are related to them, being part of the Cyprinidae family which includes carp, goldfish, rasboras, barbs and loaches. They come from South East Asia and inhabit everything from mountain streams to rivers, ponds, lakes and marshes.

There are about 30 species of danios and another 40 species of Giant danios, many of which are kept in the aquarium hobby. What's great about many danios is their tolerance of water temperature, meaning that they can be kept in standard tropical aquaria with a heater or indoor "coldwater" or temperate aquaria, with no heater, just like goldfish. They are tolerant of new aquariums, blips in water quality and the odd mistake too, making most of them perfect for beginners. 

Zebra danio, Danio rerio

Zebras are the most popular danio available and are known in America as Zebrafish. Zebrafish are also famous for their use in genetic research and can even repair their own hearts. Some have even had Jellyfish genes implanted which make them glow - a patented process that gives them the name GloFish, as they glow neon colours under ultraviolet light, but they aren't legal to be sold or kept in the UK. 

Every LFS sells Zebra danios and they come in the natural stripy form, a golden variant, a long-finned form and a spotted form called the Leopard danio. They are great for tropical or temperate tanks over 40 litres, are very easy to keep and may even breed, with the larger females scattering eggs into plants. They are best in groups of five or more and may jump out, so only keep them in aquariums with lids, or lower the water level slightly. They grow to just 4cm in length. 

Easy danios for fish tanks

Other easy danios include Pearl, Kyathit, Hikari, Kerri, Spotted, Gold Ring and Glowlight, and they can all be kept in the same way as Zebras or even with them in a mixed shoal. Glowlight danios add red colouration for those who want more colour and Gold Ring suit very small tanks as they are adult at just 2cm in length.

The last twenty years have seen a boom in new Danio species discovery and rediscovery and although small, cheap fish, some are highly desirable to South-East Asian and hillstream fish collectors. All can be bred and all are easy to keep, yet the rarer species are sought after and invite ichthyological discussion. 

Celestial pearl danios

Danio margaritatus is a wonderful, relatively new species that has only become available in the last ten years. They naturally inhabit small ponds in Myanmar (formerly Burma,) but are now bred in captivity for the aquarium market. Although related to Zebra danios, these fish are much smaller and don't pace up and down the tank like their cousins, instead flaring and showing off to each other in midwater.

The main draw with these nano fish is their striking colouration and pattern, making them very popular for small nano tanks and planted aquaria from just 19 litres upwards. They appreciate quiet, mature tanks with other similarly sized tiny fish and shrimp, but unlike other danios they aren't for new or unheated aquaria. They can be bred too. 

Giant danios

Giant danios are like danios on steroids, some growing to over 4" in length and due to their activity, needing large tanks of 90-120cm long. The most popular species is the Giant danio, Devario aequipinnatus, and they make great medium-sized fish for larger tropical aquaria. Their high speed even makes them suitable to be kept with some cichlids as dither fish, taking the male cichlid's attention away from females.

Giant danios inhabit fast-flowing rivers and streams so appreciate lots of oxygen and strong water flow provided by two internal or external power filters, or additional flow from wave-making pumps and powerheads. A long tank set up like a hillstream is perfect for them, coexisting with loaches and barbs as they do in the wild. 

For those with unheated aquaria there are temperate giants too, like the Bengal danio, Devario devario, and the Moustached danio, Danio dangila. Giant danios eat any foods and all are easy to keep, but they may jump so beware. 

How to set up a tank for danios

For small danios like Zebra danios, the more space you give them the more they will use, so a 60cm, 54 litre tank is a good starting point and will also enable the addition of other community fish. Use an internal power filter and a 50-watt heater if wanting tropical, or no heater if keeping them at room temperature. A small air powered sponge filter powered by an airpump should be used if wanting to breed them, as the gentle filtration of the sponge filter will prevent the eggs and fry from being sucked in. 

Decorate the tank with sand or gravel, rocks, wood or ornaments and live or artificial plants. Leave room along the front of the tank for the Danios to use the whole length of the tank for exercise. If you wish to create a hillstream tank like the habitats that some come from then smooth stones and gravel are all you need. Add filter bacteria, add the fish and a tank full of danios should be plain sailing! For giant danios just stretch the tank to 120cm and 240 litres.  

Danio species

Zebra danio, Danio rerio

Leopard danio, Danio rerio

Pearl danio, Danio albonubes

Rosy danio, Danio roseus

Orange finned danio, Danio kyathit

Blue danio, Danio kerri

Spotted danio, Danio nigrofasciata

Gold ring danio, Danio tinwini

Glowlight danio, Danio choprae

Celestial Pearl danio, Danio margaritatus

Panther danio, Danio aesculapii

Yoma danio, Danio feegradei

Emerald dwarf danio, Danio erythromicron

Giant danio species

Giant danio, Devario aequipinnatus

Malabar danio, Devario malabaricus

Bengal danio, Devario devario

Barred danio, Devario pathirana

Queen danio, Devario regina

Moustached danio, Danio dangila

FAQs on Danios

How many danios should be kept together?

Danios should be kept in groups of five or more. Danios are schooling fish which feel more secure in numbers.

What size tank do danios need?

Upwards of 19 litres for nano species, 40 litres for Zebra danios, but 240 litres and 120cm long tanks for Giant danio species

Are danios friendly?

Yes all danios are friendly. If they follow other fish around it means they need more of their own kind to shoal with. Danios are peaceful fish and not aggressive.

What fish can live with danios?

Any community fish species can mix with danios from barbs, rasboras, gouramies and tetras to rainbowfish, small catfish, loaches and dwarf cichlids. Livebearers are fine to mix with danios too. Just make sure the Danio's maximum water temperature isn't exceeded and don't mix them with any large or predatory fish which may eat them.

How many giant danios should be kept together?

Just like with smaller danio species, Giant danios should be kept in groups of five or more.

What fish go well with giant danios?

Giant danios go really well with other freshwater fish from fast flowing rivers like loaches, but they can mix with medium sized cichlids like angelfish, medium sized barbs, or rainbowfish.

How long do giant danios live?

Giant danios should live for over five years in the aquarium.

How big can danios get?

Most danios only reach 4cm but some Giant danio species can and do reach 15cm/6" in length and at that size these fast swimming fish need lots of swimming length and a long tank.