From what you write, I don't see any reason for worry or even mentioning any treatment / medicating. There isn't a problem. Yet. The fish behaves healthy. Has an outstanding diet - kudos to you. The splotches are clean.That's an interesting thought, about the body being disproportionate. I'll keep an eye on them to be sure of what's happening, regardless of if I know how to treat it .
It's worth noting that I keep a stick of relatively fresh zucchini in my tanks for my plecos. This sun cat has lived in common tanks with those plecos and never showed much interest in veggies. I've tried 2 or 3 different types, so maybe exploring that option would be cool.
I think the gameplan is basically observe, and base my treatment accordingly. Like theres so way to be sure at this point because the fish is active, eats well (bloodworms and Hikari Carnivore pellets) and can be seen around the tank all night long (Super active at night).
I'll be sure to update.
I agree with the close observation plan and am too interested in what this might be or will develop into.
There is no question whatsoever that the suncat is a funny looking one, short body, way oversized dorsal fin.
I don't think suncats would take any veggies; neither would synos normally but the inclusion of say spirulina or other green matter in their diet (for instance flakes) might help. I only mentioned what I mentioned as a food for thought that probably has no or a feeble connection with your case.