taken from my danio website
To sex most danios is very easy, males tend to be slim and females are more rounded.
This is not the case with Gaints, Benagals & Moustached, they can only be sexed when the female is egg-laden.
Blue danios (d.kerri) & danio hikari are the easiest as males are more yellow than blue.
This is just a guide and the author can not be held responsible for any attempts made by the reader. To successfully breed danios this is what you can do.
1) Have a smaller, cycled, tank set up in advance (10 u.s. gallon will suffice). The tank should have a few layers of marbles or larger gravel in the bottom, so the parents can not get at the eggs.
2) Place the female(s) in this tank alone for 24hrs. After 24hrs add the males (A 2 males to 1 female ratio is best, but 1 to 1 will work)
3) Leave nature to do its thing. Spawning will normally occure at dawn but can happen at dusk. If not successfull on the first day leave for another 24 hrs.
4) Remove the parents back to your main tank and raise the temperature in the spawning tank to 81f/27c.
5) Day 2, you should see little fry hanging on the glass.
6) The fry become free swimming with in 36hrs of birth and should be fed on infusoria (liqued fry #1) for about a two weeks.
7) You can now feed the fry crushed flakes and/or baby brine shrimp.
8) When the fry are large enough, around 2 months, you can lower the temp to the normal settings and/or put in with adults.
here is a male and female together; the female is in the foreground
