Well the longfin barb (whatever it really is) has only gotten that fat in the past couple of weeks, before that it looked (as far as body-shape) just like the other barb. Are eggs even a possibility? The thing is, if it's a giant belly of fungus/parasites/infections, I'm going to want to move that barb into its own tank ASAP.
The tiger's nose doesn't look like cotton wool. It was originally just a small bump, the same color as the rest of his nose, but now the end of the bump seems to have kind of "erupted" into what looks like an open sore that's kind of pinkish in the worst spot.