They are very prolific! Mine just laid eggs, again. Jacks are a pure species and the Electric Blues are a color varient of the JD - mine are normal JD's that just happen to be very blue. I want to breed the EB's with mine - I think they will produce spectacular fish. But, I'm biased lol.
If you're interested in regular JD's I have a few that are already coloring up beautifully - they are only 4 months old and around 2 inches. I was planning on taking them to a lfs for trade/store credit - but if you want some I'd be happy to pull a mix of sizes - females tend to grow a bit slower so if you only take the biggest you lower the chance of a breeding pair.