I don't think it is bull but it is a very poor explanation for what he has accomplished.
The first slide show shows the "adult" color of that hybrid monster coming out. At the end he does show a different species and the various pictures do not follow one fish but does show the transformation he has gotten those fish to do through selective breeding.
The EBJD slide show is a poor rendition of a known fact. You can't breed two EBJD together and get viable fry. What you have to do is breed two normal looking JD that carry the gene for EBJD. Because that gene is recessive you don't see the expression until they have offspring.
My take is that his skills with fish outstrip his explanation ability. So he is quite confusing. With what he is showing being possible the only question remains is whether he is doing that or just blowing smoke.