My tank is falling apart

[fishmonger]

My giant danio's stomach looks like it's going to burst. He can't swim upright anymore. I have been noticing his stomach getting fatter, but I thought he was just eating alot. Anyway, he can hardly swim and his face is very pale.

10 gal
2 giant danios 1m/1f
1 tiger barb
1 otto

I was going to use the 2 giant danios to cycle my 75 gal when I get it, but now i'm considering not even keeping fish anymore. I just lost a dwarf gourami a few weeks ago to finrot. I do 10% water changes weekly and have checked the water for ammonia and nitites and neither came up on tests. Tank has been set up since oct of 04. Please help...
Thanks in advance

 

[Devilishturtles]

Hmm. Where are you getting your fish, and how are you acclimating them? Two giant danios (if they are as giant as I've seen in some pet stores around here) are too much for a 10 gallon tank, IMO. Could be just bad fish, and not you. What kind of test kit are you using to test?