Fish seem fine but are very thin, lost 2 already

[ips]

I have a community tank with sharks, mollies, guppies, clowns, tetras (various) etc and I have had 1 rummy nose tetra, 1 dalmation molly and 1 silver shark all eating /swimming and appearing completely normal apart from being very thin.

Of the 3, only the shark is still alive. His fins aren't clamped or anything, yet he is still thin. I fear that he too will go the same way as the other 2 if I don't do something.

All the other fish are fine.
Ammonia, nitrate, nitrite all 0, ph 7.0, temp 26 - 27C (78 - 80F).

Please help what can I do.

 

[gadazobe]

Sounds like he may have internal parasites. Is he eating? I think fish can also get worms - can you see anything protruding from his bum?

 

[ips]

Eating fine and nothing protruding from his bum. If it is parasites, is there anything I can add to the water that won't have any effect on the other fish?

 

[gadazobe]

I know that Interpet do a whole range of medications for tropicals - if I remeber rightly they do one for internal parasites. Best to go to your lfs and ask what they recommend - explain what's happening to your fish to them and most of them are very helpful.