Short-bodied fish have always been around, or at least for 20+ years. Balloon mollies, balloon rams, etc. are all short-bodied fish.
This is nothing special. It is a spinal deformity — a birth defect that causes a short spine. The body cavity is now smooshed into a fish that is 2/3 to 1/2 the length it should be, which is why the fish balloons out — all the same organs now have to fit into a much smaller body, so they expand outward.
I find these in cichlid fry all the time, even in F0 pairs. Responsible breeders would cull them to keep those problematic genetics from being amplified in future generations, but of course the people who breed fish for this hobby on a large scale are rarely concerned with being responsible. We’ve seen dyed fish, injected fish, hormoned fish, tattooed fish, veil fins so exaggerated that fish struggle to swim, and so on.
Lately there are a lot of Asian members on Facebook cichlid groups proudly showing off deformed Geophagus and it bothers me because these genes get passed on and muddy up decent genetics. A great example are “bulldog” discus, the short-body version of a discus. The spine is shortened and so it pulls in the face and tail, giving the fish a bulldog face and a body that’s almost hourglass shaped instead of round. These fish were then bred into nearly every bloodline to try and improve the shape of existing discus strains. The thought is that it would help make the resulting fry more tall, or “standing egg” shape as the Asian breeders call it. While it does create impressive discus, it also causes a significant number of fry in subsequent generations to be deformed and heavily short-bodied. Now those genetics exist in most imported discus, and rear their ugly heads when breeders work with those adult fish.
The short-body fish also get mislabeled and misrepresented. For instance, “polar blue parrot convicts” is the new craze in all the fish stores around here. I’ve been told by countless clueless store employees that they’re a new strain created with convicts crossed with jellybean/blood parrots. I don’t think this is true at all. I think that’s the thought because the shape “looks” like parrots, but in reality parrots are notoriously deformed and short-bodied as well. IMO the new convicts are simply short-bodied cons that are probably some form of HRP or platinum convict crosses. I doubt there is parrot in the line anywhere. But that’s how they’re being marketed.
This is an F1 Heros severus ‘Curare’ from my wild pair. It’s a cull. The myth that these are rare, specially-created fish that the hobby makes them out to be is just false. Also, FYI, I don’t buy into this idea that because it’s shorter, it can be placed in a smaller tank. It’s still going to have the same aggression, appetite, and bioload as its normal siblings.
