It's from Jeff Rapps. I'm not sure that inbreeding is the cause. But whatever. Raise enough fry and some deformities will arise. The tail is fine. I'll give you a hint. The problem lies in front of the first bar.
The fish has no pectoral fin on it's left side. I'll try to take a better picture from in front or behind later, but it's plate completely absent. The area behind the gill plate has no peduncle at all. It's like the whole fin and attached muscles are absent. Again, I'll try to get better pictures. Great observation with the less than ideal pictures Ken!
Isn't that batch of Bahia from borchbuilds pair?? My guess is that there is in breeding. When you have 1000s of fry I'd imagine you are going to run into some deformities.
Not necessarily a defect. It's most likely due to malnourishment. Just keep feeing him feeder until he's 8in+, after that pellet training wouldnt hurt. When he bulks up, his tail should be proportionate to his body.