Poorly Penguin

I've just found a penguin belly up and stuck on the filter intake. He's still alive and breathing but doesn't look like it's got any buoyancy. Is this a swim bladder problem?
I've but the poor soul in a hatchery so it's put of harms way. (the Krib fry are still with dad) I've given a bit of food and has been trying to feed but with little success.
There doesn't seem to be anything else wrong, no white spot or other injurys/infection.
There's been a bit squabbling between the shoal, so I'm assuming he's been hit hard by a tank mate.
Is there anything I can do?

I thought that might be the case. Thanks Sue.

Fry are usually the first to suffer, but I have had an exception to that. Several years ago I had pure endlers (bought from breeders who could trace them back to the wild). Being livebearers, the tank had adults and fry. I found some pencilfish I'd been looking for for ages and put them in the same tank without quarantining. The pencilfish all died within 24 hours, then the adult endlers died one by one. I ended up with a tank of nothing but endler fry.

How long have you had the penguins? Some diseases can take several weeks to become apparent. Or perhaps the female krib was sick when she died not just bullied by the male, and she's passed something on.
The other thing that springs to mind is the male krib. Is he being over protective?

I am reluctant to suggest adding a medication with fry in the same tank - assuming the hatchery you mentioned is one of those that goes inside the main tank. If you have somewhere you could medicate the penguins away from the main tank I would suggest trying eSHa 2000 as the best we can get in the UK.