Zebra danios versus white-skirt tetra?      2/16/14
Hi wonderful people.  Thank you once again for running this marvelous site!
 I have what is hopefully a simple question.
<Let's see>
I just set up my first freshwater low-tech (low light, no CO2) heavily planted tank, 46 gallons.  I cycled it fishless (ammonia method), which went incredibly well.  I don't know why more people don't do it that way, as it is so fast and easy. 
<Agreed>
After just three weeks I can put in ammonia to 2 ppm, and in 8 hours ammonia and nitrite are unmeasurable.  But I digress.
<Take your time; we are all friends here>
I initially stocked it with 5 albino bronze Cory cats, who seem to be happy and healthy.  I was browsing the LFS with my wife, and she squealed in glee when she saw the GloFish.  My heart sank.  Over my dead body.  But she has been so wonderful to me, allowing me to have three reef tanks and now a freshwater tank all over the house, that I just can't say no to her pleading to get a school of them.  Sigh.
But here's my question:  They have two varieties of GloFish, Zebra danios, and Tetras (white-skirt I think, but not positive).
<Yes; Gymnocorymbus ternetzi... modified>
 In terms of care (feeding ease, health, proper social behavior), which do you think would be easier to keep?
<The Zebra Danios; but they're both close... the Blackskirts/Tetras being a bit more nippy>
One added factor is that I think I have room for one or two of some other 'feature' fish, and I'd love to get something striking in a different way. 
A pair of Angels would be nice, but their temperature doesn't overlap enough with danios.  A male Betta would be nice, but I'm sure it's tail would get nipped.  Maybe a pearl gourami or two?
<These last, Trichogaster leeri; would be best w/ either of the two gene-clipped onto fishes>
Any advice, especially on Danio versus tetra, would be deeply appreciated. 
Thank you in advance!
<Welcome. Bob Fenner>
Tim
Re: Zebra danios versus white-skirt tetra?      2/17/14
Bob - Thank you.  You and the folks here are wonderful!  If I may, I have one quick follow-up.  From my research around the net and in some books, it appears that the white-skirt tetras are more tolerant of pH swings than zebra danios.
<Mmm; I'd rank them near the same... both species have been under human culture for four or so decades... tolerant of human abuse>
  Even though my tank is completely cycled, it's still young, and over a 24-hour period its pH swings between 7.4 and 7.8, which concerns me a little.  Do you think danios can handle this better than the tetras? 
Thanks!
<I would say so; yes. BobF>
Tim
Re: Zebra danios versus white-skirt tetra?
Bob - Thank you!
Tim
<Ah, welcome. BobF>

Re: Fish to add     3/13/12
Hi there, one follow-up question.  My daughter is interested in Angelfish.
Those are not on your list below, but could they work with Corydoras and Zebra Danios? Again, thanks so much for your help!
Sue
<Angels can work, but only just. Corydoras and Zebra Danios will tolerate water up to 25 C/77 F, which is at the low end of what farmed (i.e., average pet shop) Angels accept. Wild Angels will need rather warmer water to do consistently well, around 28 C/82 F, so you'd keep these with Corydoras sterbai, the classic "warm-water Corydoras". As for water chemistry, Angels prefer soft, slightly acidic water, just like the other two species, but all three can do fine up to 20 degrees dH, pH 8, even though it isn't optimal. Angels normally ignore Corydoras, and if the Danios are in a big group, there's little risk of fin-nipping. Cheers,
Neale.>

help!    9/8/11
hi guys, wondering if you can give me advice, I have just bought a 95 litre tank, I have:
5 zebra Danios
2 Dalmatian mollies
3 cat fish
9 neon tetras
2 female guppies (fancy red tails)
4 coral red plattys
my problem is my zebra Danios have killed 3 Neons and 1 of the guppies (I have the other in a separate dish floating at top of tank as they were attacking her) do I add more Danios to stop this problem or do I take them back to the pet store and add other fish. I am a beginner and want to get this right. could you also advise me which other fish to add that will mix well with the other fish I have already. thank you so much for any advice you can give me
<Hello Jennifer. Zebra Danios can be aggressive, especially when kept in small groups. Six or more would be safer. But even then, Danios are often very aggressive towards small surface-swimming fish like White Cloud Mountain Minnows. That yours attacked Neons is unusual because Neons stay close to the bottom of the tank most of the time, so they don't really interact with the Neons. While the science suggests adding five more Danios would work, I can't guarantee that, and you might decide to forget about
them in favour of something less aggressive, like White Cloud Mountain Minnows, Galaxy Rasboras or more female Guppies. Cheers, Neale.>
Re: help!    9/8/11
thank you so much for your help, I think the best option is to take the Danios back to the shop. they more than most stay at the top of the tank then when they have killed the fish they circle it until we remove the dead fish. I will look up the fish you have advised thanks again for your help
<Glad to help. You might find these useful:
http://www.wetwebmedia.com/ca/volume_5/volume_5_3/stocking.htm
http://www.wetwebmedia.com/FWSubWebIndex/fwlivestk.htm
http://www.wetwebmedia.com/FWSubWebIndex/EthicalAqArtJHelfrich.htm
http://www.wetwebmedia.com/FWSubWebIndex/HardWatrCommTkStkMonks.htm
Cheers, Neale.>

Zebra Danios... Mis-mixed, comp.     6/14/11
Hi I have got 5 zebra Danios 6 black phantom tetras 1 crown tail fighter 1 Plec and 3 black moor gold fish in a 300ltr tank with a 900ltr an hour filter system. My question is about my Danios they where fine at first kept to them selves and just chased each other around the tank, but over the past week the Danios have been chasing and attacking the other fish they have taken chucks out off all the black moors tails and dorsals and they have killed 4 of the phantom tetras and now have started attacking the fighter But they haven't bothered with the Plec. I've Done a ph test as well as several others and all is fine the water temp is 28 im feeding every other day. I just cant work out what the problem is any help would be much appreciated. I don't want to get rid of the Danios as they are really nice fish but if they keep attacking my other fish they will have to go.
<Hello Lee. What you are describing is entirely normal with Danios. They should never be kept with fancy Goldfish, and yes, they tend to bully smaller schooling species as well (the classic victims are White Cloud Mountain Minnows, another low-end tropical species often kept in unheated tanks). Bettas are poor companions for Danios because they require totally different environmental conditions, i.e., temperature, water current. In short, Danios should be kept with active midwater species like Tiger Barbs as well as armoured catfish, loaches, etc. Cheers, Neale.>

Zebra Danio Compatibility 03/20/11
Greetings!
I have a relatively new 40 gallon aquarium (~5months). The tank dimensions are 50"L x 12"D x 16"H. The substrate is all large limestone gravel/stones (ranging from 0.25" to 1") but mainly large stacked flat limestone rocks that form many caves. There are no live plants right now, but large bunches of fake plants that create many hiding places. The filter is quite strong, running a hefty 350GPH of 7.5-8.0pH water through a Biowheel and a temperature of 71 degrees consistently. There are currently 8 zebra Danios living in the tank that are healthy and fed flake food every other day and bloodworms once every two weeks. My question for you kind folks is regarding my stocking options. I would like to increase the size of the school to 14 zebra Danios and add a "centerpiece" fish. Due to the strong current, large substrate, and elevated pH, I feel that I have ruled out many of my options. I would prefer to stay away from any bottom-dwellers and am leaning more towards something that is bright, solitary, on the larger side (in contrast to the Danios), but also peaceful. I'm not very familiar with exotic species but read a few articles about red-tailed black sharks. Do you have any suggestions for me because I am really stuck!
All feedback is really appreciated!
Much thanks,
-Hannah
<Hello Hannah. You actually have a good range of options to choose from.
For a start, there are multiple Danio species! Contrasting a large species with a smaller species can be worthwhile. Devario aequipinnatus and Devario malabaricus are two of the more widely traded "giant" Danios, and while predatory to be sure, they shouldn't cause problems when kept with adult Zebra Danios. Devario regina and Devario devario are slightly smaller and quite a bit less pushy than the "giant" Danios and should be completely safe with any fish too large to swallow whole. Other good options would include Garra species, of which several are traded, some of which are quite colourful, as in the case of Garra flavatra. Garra behaviour varies from more or less schooling through to downright territorial. I keep one of the territorial species, Garra cambodgiensis, and while it does chase fish around the tank, it's also great fun to watch. Swordtails are another group of fish that enjoy water current and lowish temperatures, and they should thrive in your tank if you upped the temperature to 22 C/72 F. Another group of livebearers to explore would be the Goodeids. Of the two widely traded species Ameca splendens might be a bit nippy for this tank, Xenotoca eiseni a bit less risky. But they're both very pretty and perhaps worth a shot; I keep Ameca splendens and they're terrific fun to watch and breed.
Most other members of this family, such as Ilyodon whitei, aren't nippy at all, but they're less widely traded, so you may need to hunt around for them. Goodeids are curious, greedy fish, and this makes them a great midwater contrast to surface swimming minnow-type fish like Danios. What else? Red-tail sharks wouldn't be my first choice because it prefers warmer water and a larger tank than you're offering, though it does work well with Danios. Blue Acara enjoy coolish conditions, and if you wanted a cichlid, one of them might be a fun "pet" fish for midwater. There are quite a few other low-end tropical cichlids such as Port Acaras and Keyhole Acaras that do well at 22 C/72 F upwards, but getting hold of them may or may not be easy in your area. If you have really good water quality, the Paraguay Eartheater cichlid Gymnogeophagus balzanii is definitely worth considering, but like all Geophagines it is sensitive to nitrate, and does of course need a soft sand substrate rather than gravel. On the other hand, it is perfectly happy in the 18-22 C/64-72 F temperature range, making it a prime candidate for a cool aquarium. Hope this gives you some ideas. Cheers, Neale.>

I was wondering, will zebra Danios and Glofish school together?  2/1/2010
Dear Crew,
I was wondering, will zebra Danios and Glofish school together? I know they are actually the same species, but Glofish are just genetically altered.
Thank you.
<They school together just fine. Zebra Danios are hardier though, and likely to be more resistant to disease, and it's not inconceivable that they could be carrying pathogens the Glofish can't handle. Quarantine each carefully before combining. Cheers, Neale.>
Excuse me, but what do mean by quarantine them and then put them together? 2/1/2010
<When you buy a new batch of fish, keep those fish in their own 10 gallon aquarium before adding to an existing community tank. After 6 weeks of quarantine, it should be obvious if the new fish are healthy or not. If they're fine, add to the existing collection of fish. Glofish are, unfortunately, bred to a price rather than a quality, and the standard of specimens I've seen in US pet stores has been middling to poor. I wouldn't take any chances with them. Cheers, Neale.>

Why is it so horrible to put a school of zebra Danios and a common goldfish together? 2/1/2010
Dear Crew,
Why is it so horrible to put a school of zebra Danios and a common goldfish together? Is it the waste? I have a filter and always change the water?
Thank you very much
<It can be done. But it depends on the aquarium. Goldfish are messy, and unless the tank is very large, and very well filtered, they tend to produce poor water quality. But if, say, you had a 55 gallon tank equipped with a
filter rated at 4-6 times the volume of the tank in turnover per hour, you certainly could mix a couple of Goldfish with a school of Zebra Danios. You would of course need a heater to keep the tank somewhere around 20-22
degrees C (68-72 F). Although Danios are tolerant of fairly cool conditions, they won't thrive in cold tanks, especially during the winter.
Cheers, Neale.>
Re:
Just one more question. What if I put one common goldfish with seven zebra Danios in a fifty gallon aquarium with an Aqueon system five filter?
<What about it? Read my last reply. States clearly what criteria you need.
Find out that gallons/hour rating for your filter, check you have a heater of appropriate wattage, and see for yourself. Cheers, Neale.>

Brachydanio; Betta; compat.   1/18/10
Dear Crew,
I have a ten gallon aquarium with 6 zebra Danios in it including a heater and a pretty powerful filter.
<Too small for Danios... this species gets fairly big, around 5 cm/2 inches, and just look at how fast they swim! Anything less than a 20 US gallon tank just isn't fair. Do read here:
http://www.wetwebmedia.com/ca/volume_5/volume_5_3/stocking.htm
>
Can I acclimate a Betta into my aquarium even though I have a pretty powerful filter, because I have heard they do not like powerful currents. ( I have had this Betta for quite some time in a gallon aquarium {spare me:)}
and I think it's time I move him)
<No; mixing Bettas (which need gentle currents) with Danios (which need strong currents) won't work. Furthermore, Danios need quite cool water, around 22-24 C (72-75 F) to do well, whereas Bettas want it much hotter than that, around 28 C (82 F) being ideal. There's no overlap between the needs of each species. One comes from streams, the other from ponds. On top of that, frustrated Danios will nip at Bettas.>
Thank you
<Do spend some time researching the needs of fish PRIOR to purchase. Pet shop staff often clueless (some aren't, but often Saturday teenage staff hopeless), web pages variable in quality at best. But there are lots of good books out there, as well as us! Cheers, Neale.>

Re: Brachydanio; Betta; compat. 19.01.09
Yes, thank you very much
<My pleasure. Cheers, Neale.>

Shrimp and cardinal tetras   12/6/09
Dear aqua experts,
<Hello Janet,>
I have only found conflicting advice in trying to find the answer to my question, so I come to you to get my answer. I have 2 established freshwater tanks. The 10 gallon houses 14 red cherry and Amano shrimp as well as 10 zebra Danios that are about 6 weeks old and growing.
<Very good.>
The 20 gallon houses 3 zebra Danios and 6 cardinal tetras.
<I'd up the number of Cardinals if you could. I'd also make the observation that Danios prefer cooler water to the Cardinals, so one or other group of fish isn't going to be completely happy. 25-26 C would be about the best
compromise, but even then, not ideal.>
I would like to move the Danio juveniles into the 20 gallon with their parents and have a Danio-only tank.
<Very wise. Danios like things on the cool side, around 22-24 C.>
I would like to move the cardinals into the shrimp tank.
<Okay.>
Both tanks are planted, the 10 gallon heavily. I'm sure (?) the shrimp are very happy in their current tank with only some baby Danios to keep them company. Can I add the cardinals to the shrimp tank (after I move the baby
Danios) without the shrimp becoming reclusive, boring, anxious and eaten?
<Yes; Cardinals pose minimal threat to the Shrimps, even Cherry Shrimps, and the two species will coexist nicely. Since Amano shrimps like things a little on the cool side, they're ideally kept with Danios rather than Cardinals.>
Thank you all knowing ones.
Janet
<Cheers, Neale.>

Pandas and Barbs Incompatible? Hi! I have a 10 gallon tank with 2 striped barbs and 2 long-finned Danios. All 4 fish are about 1" in size.  Tank has been cycled and water tested. They have been living together for a few months now and get along great. I do a 20-30% water change every week.  The other day I added 2 small panda Corys.  Right away, one striped barb started chasing one of the Corys.  This went on for a few days. Every time the panda tried to rest, the barb would seek him out and chase him.  It only happened with one barb and one panda.  Also, the barbs were hogging all the food, so we tried a sinking pellet for the pandas, but the barbs found that too and devoured it!  Needless to say, when I got home from work one night, both pandas were dead. I took them out and did a water change and the 4 original fish are back to normal.  Will this happen with any new fish I add or was there some incompatibility with the panda and the barb?  I feel like the barb harassed the pandas to death!! < Some fish do get territorial and some barbs have been known to become fin nippers. Next time do a water change and rearrange the tank just before adding any new fish. This may help. Or you could try to add numerous fish at the same time to help disperse the aggression of the barbs.-Chuck> Thanks, Frances

Danio We recently set up a 48 gal tank and we purchased 4 Long Fin Zebra Danios. One of the Danios is chasing the other three and actually taking pieces out of the other tails.  The pH is 7.6 and all other readings are in spec. The aggressive Danio is not bothering the other fish in the tank.  It seems the other 3 non-aggressive Danios are not bothering each other, it is just the one that is aggressive. Should we isolate the aggressive fish?  Any help would be greatly appreciated.  Love you website. < You could either add more Danios or take out the aggressive one. I am afraid that if you remove the aggressive one then another one may become dominant and chase the others as well. A 48 gallon tank should be big enough so that they should have room to get away. I usually recommend that schooling fishes like these be kept in groups of at least 6.-Chuck> Bob