Originally Posted by indjo
This may sound cruel, but this is a strategy used by many breeders, including myself;
If the female is older/ bigger, keep her in a smaller container. I often use 1-2ltr bottles. Deliberately stunt her growth. But the male must go in a big tank so he can grow faster. Feed the male excessively (I use frozen bloodworms). You can also use this method anytime you plan to breed back to mom.
Make sure the male has clean white body, not silverish-grey. Black dragons usually have silverish-grey body. Bred to clean white body may produce silver body with what ever light colored fins or may have "dirty" looking body.
I do this too...females in a small container (unless they are runts...then they go into a large container...lol), males should go into at least a 1g. Water needs to be kept around 83*-86*F to also help with growth. High Protein foods (IMO bw tend to pollute the water too fast...BUT I will feed them the morning of a water change!!!). I prefer live foods that I gut load with other foods.
She is a PK, so he MUST be her size before you attempt to spawn them. With her being bigger, she will be to aggressive for him. I'd also get her bored with other fish...keep him where he can't see fish. She will be less likely to be aggressive if she is bored looking at her "friends".