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This week, I will profile a common cyprinid, one that is often used to cycle tanks. The zebra danio is a very hardy, usually peaceful tropical fish that is great for a new fishkeeper.

The zebra danio (Brachydanio rerio, Ciprinus rerio, Danio rerio) is a cyprinid from India. They are one of the toughest fish around, and they frequently survive tank meltdowns, ammonia spikes, etc. Though they will thrive in pretty much any water parameters, they are most partial to slightly acidic (about 6.8), soft water that is heated to 74 degrees F (23 degrees C). They like current, so that should (preferably) be provided. Also, some hiding places in the forms of decorations or vegetation should be provided, but with plenty of open space. This fish is very active, so they need room to move around in. The zebra danio needs to be kept in groups (six or greater is best), because they are shoaling. Without company, the zebra danio may become nippy or restless. In any case, they will not be as happy as they are when kept in shoals.

The zebra danio is an omnivore, and will eat a wide variety of foods. Flake foods are greedily snatched up, and make up a good staple diet. Frozen, freeze-dried, and live foods all make great treats, and will be rapidly consumed. These danios are such fast eaters, that they will sometimes eat your other fishes food as well. Care must be taken to ensure that tankmates get their fill.

The zebra danio is a relatively small fish, topping out at only 6 centimeters (2.5 inches). They do not need a super large tank, though the more space they have, the more room they have to swim. As they are very active, tanks of seventy-five liters (about twenty gallons) are great, because they provide these fish with all the room they need to swim in. As I already mentioned, they can be kept in just about any type of water. Of course though, clean water is always best. They can tolerate low amounts of salt in their water, and successfully live in lightly-salted tanks with livebearers. Still though, pure freshwater is best.

The zebra danio is a pretty peaceful fish, and fit for a community tank. They usually do not bother slightly smaller tankmates, and are often quick enough to escape from the hungry jaws of larger fish. That having been said, they can become nuisances, nipping at fish with long fins. They have been known to kill bettas and angelfish, and gouramis are probably potential victims, as well. If you are planning to put these fish in a community tank, it is best to exclude long-finned fish as potential tankmates. As has been said, they are best kept in shoals of at least six. The more danios there are, the smaller the chance that they will pester tankmates. However, sometimes slower fish can be intimidated by the constant swimming actions of the zebra danio. If that happens, the slow fish will be driven towards the top or sides of the tank, and possibly become too nervous to eat. Just keep that in mind when planning a tank with these danios in it.

Sexing these guys is not too easy, but it can be done. As with many other cyprinids and characins, the female zebra danio is larger and fuller than the male. Females are probably larger than males, so that they can house a good-sized ‘egg factory’. Also, males tend to be a little bit more colorful.

Zebra danios are easy fish to identify. They have brownish backs, with alternating gold and blue horizontal stripes on their sides. They have similarly-colored fins, and white bellies. These fish have two pairs of barbels around their mouth, as well. They come in ‘normal’ and long-finned varieties.

Here are some pictures of the zebra danio:




These danios are great for any beginning aquarist that wants to keep interesting and active fish. They are also popular with more advanced hobbyists, who enjoy the personality of these fish. These danios are often bought for the purposed of cycling a new tank, because they are some of the toughest tropical fish alive. I recommend the zebra danio to anyone who has never kept fish before, and is looking for a place to start.

Some links: http://freshaquarium.about.com/cs/cyprinids2/p/zebradanio.htm
http://fish.mongabay.com/species/Brachydanio_rerio.html
http://nis.gsmfc.org/nis_factsheet.php?toc_id=169

[link=Week One- Betta splendens (Siamese Fighting Fish)]http:// www.fishprofiles.com/files/forums/General%20Freshwater/50279.html[/link]
Week Two- Carassius auratus (Common Goldfish)
[link=Week Three- Pterygoplichthys pardalis (Common Pleco)]http:// www.fishprofiles.com/files/forums/General%20Freshwater/50899.html[/link]

If there are some errors in this week's thread, please forgive me. I am not well-versed in the way of the danio. I tried to make my information as accurate as I could, but mistakes may have been made. Thank you for your patience.[/font][/font][/font]

Last edited by sirbooks at 15-Dec-2004 20:16

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And when he gets to Heaven, to Saint Peter he will tell: "One more Marine reporting, Sir! I've served my time in Hell."

And don't forget the GloFish -

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-Molly
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Yes dont forget the glofish. To bad they are so expensive like 10$ a piece around here. At least there not dyed.Great article books

I keep leopard danios with all the fish you mentioned that danios probably shouldnt be kept with Sirbooks, and I have had no trouble.
The only trouble I had is when I introduced 2 new leopard danios, a male and a female, to my group of 4 (1 female 3 males). Unfortunately, the female danio I already had didnt like extra female company and murdered quite viciously her companion.
My betta chases this large female danio, having great fun, but the danios have never shown aggression to other fish species than their own. I keep them with a Betta, 2 angelfish,3 gouramis, etc etc.
Good article though. You should mention that leopard danios are essentially the same fish, just a different color type.

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Yes, leopard danios are similar to zebras. However, they are less common (in my experience), maybe slightly less hardy, and they are a different species. I didn't really want to include them in the article.

As for compatibility, I have heard horror stories about zebra danios killing angelfish. I assumed that they would have the same attitude towards gouramis, as well (since they also have long fins). The zebra danio profile mentions that this fish can become nippy, and the favorite target of nippy fish is long fins. Still though, this is basically just an assumption. Like I said earlier, I really don't have experience with this fish. I cannot refute or confirm your claim. Maybe someone else with more knowledge than me can.

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And when he gets to Heaven, to Saint Peter he will tell: "One more Marine reporting, Sir! I've served my time in Hell."

It seems unlikely from the evidence that Leopards are a separate species, since (for example) when you cross a leopard and a zebra you get either half zebras and half leopards or all zebras, and if you cross any of those zebras back to each other you get 75% zebras, which is pretty solid proof that leopard is just a normal recessive trait. I had a leopard GloFish, actually, it was very cute.

-Molly
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I'm pretty sure they are the same species. Older books may refer to them as different species, or questionably the same species... the lack of information about their origin is the main concern in that, but I suspect they were bred out by someone who didn't know well what they were doing. If someone found a population of leopard danios that was geologically divided from zebra danios in the wild, they might have something to say they are a different species, but genetically they are very similar.

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I don't believe this has been mentioned:

The Zebra Danio lives in the upper layer of the tank. It very seldom travels to other portions. It will travel to the bottom to breed, which only takes a minute or two. You will want to keep this in consideration when planning a community tank.

It is a notorious egg-eater, so if you have any intentions on breeding this atractive species, be prepared to remove the adults or provide some kind of agg trap.

-Wayne

My danios, as well as my sisters previous zebra danios- do not hang out only at the top. Mine are primarily bottom-mid dwelling fish.
I have 4 males which 95% of the time swim in the bottom, and 1 large female who spends about 80% in the bottom, and 20% in the top- mostly when shes teasing the betta.
Perhaps I have odd danios....
or maybe too few? I did have a 6th one- a female, but the larger female destroyed her.


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Well, if zebra and leopard danios are truly one and the same, (besides the color and patterning), then maybe someone will fix that. If a person submits a Leopbra (just making up names here:%)) danio species to the scientific community, and they agree that the fish are the same, then the two fish will merge. Who knows? Maybe whoever does this can get it named after them, like a Brachydanio bob or something.

And really, I have no idea where zebra danios like to spend their time. I assumed that they would be top/middle dwelling fish, but I could be wrong. I guess they just swim wherever it suits them.

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And when he gets to Heaven, to Saint Peter he will tell: "One more Marine reporting, Sir! I've served my time in Hell."