Oh, wow. Do you have a pic of him? I'm really curious how he looks like.
Okay, still not brilliant photos, but slightly clearer. You can see his colours more anyhow. Am I mad? Seeing yours reminded me of this one of mine, but you know I'm far from a guppy expert. Do you see why I thought they were similar though?
Now, I'm also worrying. I thought these males were swallow tailed, since the yellow snakeskin male you can see in the first photo, with the ragged/uneven swallow fins is their dad, so I thought they'd all got his fin genes. But looking at these pics, it looks like regrowth at the tips, fin rot? And I can see a split in the copper/platinum male's tail that I haven't seen before
I can't decide if I'd want it to be fin rot or not. If it is, urgh, not another health issue! The water quality in this tank is always good, and weekly water changes always on time. On the other hand, I don't like the uneven ragged looking fins on some of these guys, so if it's fin rot and I can fix it, then I'd prefer how they look! Do you think it's fin rot?
Above and below is the yellow snakeskin/cobra dad, bought like that, and the one I think looks like yours, one of his young. Blues unrelated.
Below, the copper/platinum(?) male, and one of the yellow snakeskin/cobra young, clone of his dad
Potentially copper/green platinum male, and in the background, unrelated male whose tail looks fine. Wouldn't the unrelated ones also have fin rot if it is fin rot?
Another offspring of the same yellow snakeskin dad, whose colours I really love, but he has the uneven tail, including what looks like a big chunk out of the centre. Can the swallow gene produce a big chunk missing rather than just the ragged edges?
You can see the big chunk missing from the centre of the tail in that male here. But also the unrelated blue who has the normal tail, no ragged edges or chunks missing... The yellow/orange tail same batch as multicoloured one here, same dad, swallow tail like his dad, looks more normal and less ragged looking than this one or the potential copper green/platinum.
Nothing in the tank that could be nipping, only pygmy cories and otocinclus in here. Unless they're nipping each other? Haven't heard of male guppies nipping each other, there's no obvious bullying in the tank, some chasing and displaying, but no targeted bullying or intense chasing like I've seen in bully fish before.