I don't know what to think

My paradise fish seems poorly this morning. His color is fine, his fins aren't clamped, but he's hanging out near the surface again. Eats but not eagerly. I haven't seem him flashing but suddenly heard that dull clicking sound again, looked at the tank, saw him gasping for air. Later on he's hanging at the surface, fins flared but head slightly tipped down, and a guppy is picking at his side. Nipping him over and over. Laddie doesn't move for a while, then swims off a bit, the guppy comes back and picks at his spread tail. Could Laddie have some kind of external parasite the guppy is picking off? I don't see anything. Or is he so very ill the smaller fish knows he's a goner. 

It makes me feel very glum. I sorted out my young white clouds today. Five that look very flashy, bold red/black colors on the tail, broad white band on the dorsal fin seem obviously male to me, I kept in the 20H. Seven that are slightly paler, yellowish body hue and only have a small white mark on the dorsal also a bit more plump in the body from top view, I assume are female- those went into one of my extra fish bins (with small sponge filter, a few fake plants, handful of subwassertang and hornwort from their growout tank). Going to re-home those if I can. Six more I'm not sure about went back into the 20H for now. I want to keep mostly the males. 

I was thinking of switching fishes- putting Laddie in the 20H by himself and moving all the young white clouds to the 33L to finish growing up. They're still small enough he might eat them. But now I can't decide. There's tons of subwassertang in the 20H - it multiplied and multiplied! I'd love to sell or RAOK that after done keeping white clouds in there; wouldn't feel good about doing so if I had a sick fish in that tank would have to compost most of it instead . . .