Maybe a sick Rosy Barb?

[Bachiwan]

Hi all,
I have what is hopefully a non-issue, but maybe someone with expertise can help me out. I've got a school of 5 rosy barbs in a 29G tank. Four of them are fairly typical - having way too much fun with anything they find. But lately the fifth one has taken to sitting in the corner, almost moping. He doesn't get picked on, and he'll come to food, but he's not acting like a barb. Another observation is that his mouth is always open and he has little red spots on his upper lip. Can't tell if those spots are on the others.

Other info:
From the Jungle 5-N-1 Test Strip:
NO3 - 20ppm
NO2 - 0
Hardness (GH) - 150ppm
Alkalinity (KH) - 80ppm
pH - 7.2

Temp - 78deg

Barbs have been around for about a month, didn't quarantine them. Part of a community of:
5 rosy barbs
2 Bolivian rams
2 feathertail synos
1 upside-down cat
1 Asian upside-down cat
1 red-eyed tetra
1 redtail shark

Any ideas??? Thanks in advance!

[Bachiwan]

Update: his upper lip is completely gone. I really could use some advice. Should I put him down? I have him in a frye net, seperated from everyone else, but sharing the same water.

[William]

I can't tell you what the rose barb is suffering from, especially since the prolem is getting worse so rapidly.

From what you are writing i think it sound like someone is picking on him but as you say that isn't the case I don't have any idea of what it can be.

I don't know if you need to put it down but I would recommend that you isolate it from the other fish if you have the possibility. If not don't have the possibility it might be worth considering putting him down to avoid other fish getting infected but I don't know if this is necessary as I don't what the root of the problem is.

[DemonShark]

This is proubly a mouth fungus it is caused by a bactreuim and therefore hard to destroy