I think it might be bad swim bladder issues but I'm not sure...

The water in the tank is checking out fine.

Here's some story;
I got a new fish, she checked through qt quite fast/with flying colors. I put her in with Jonas (Jonas is just a tab bit smaller than the new one) Almost right away I noticed Jonas getting all floaty. I observed Clarice 'bumping' into Jonas, not attacking, more like... I'm having trouble explaining it. She would swim up to Jonas and nibble her. Only once or twice like she realized that jonas wasn't something to eat. She would also bash Jonas out of the way when swimming. I had it in my head that her bumping and crashing into Jonas caused her problems but I just don't really know. So, one day Jonas got so bad she went belly up. I put her in a hospital tank and she was just fine within a couple of days so I put her back in with the big fish. Within just a span of a few hours she was floaty again... I've been at constant war, trying to maintain Jonas's health but finally tonight, I took the big fish out and Jonas is by herself.

She is currently belly up. Alive, just not swimming. I think she is so tired out from trying to swim normally that floating belly up is all she can do. She tries her hardest to swim to the bottom and gets some nice momentum then crashes into the bottom of the tank. Then floats up so quickly that her entire face pops up out of the water...

I put in aquarium salt and covered the tank with a blanket to make it dark. I also did 40% water change.

Does this sound like advanced SB problems??? Or something else...

What kind of fish is your new addition? Some goldies are extremely prone to getting SBD.. like Orandas because of their short bodies. It may be a problem that it has had from upbringing at the store or a problem that is exsisting now.

Makes me question the water paramatars if when you put your fish in the tank it goes belly up. Could you test your water and put up the results for us. That would help out a lot. How often do you change your water and how much do you usually change? What type of filter and how long has this tank been running?

If the fish is upside down... there is a problem with it's swim bladder either temporary or permanent. I have an oranda that get's it once and a while but its in relation to slight higher levels in the tank. So I tend to do water changes more frequently there.

You could fast the fish for a couple days and feed it frozen peas. Not only do they love it... but it's suppose to help in that department. Try it for a couple days and see what happens.

If you could possibly answer as many questions up above as you can,that would help.There are just so many factors of what could be going on with your tank.

Sorry I'm just getting back to this now. Not only do I have fish trouble but some nasty computer problems.

Both fish are Orandas but the one in trouble is clearly less Oranda than the new one. The fish in trouble looks vey much like a Fantail just with a head growth.

The current water reads:

Ammonia: 0ppm
Nitrite: 0ppm
Nitrate: a little over 5ppm

The tank is 30 gallons, been running since mid June.
Right now I only have the sick fish in the tank. However, she was living with the new fish until I noticed her getting really floaty.

I forgot to mention this above but the sick fish not only floats but pretty much from the time I'm awake to the time I go to bed (about 9am till 1am) she can be seen GULPING back the air. I have two filters running in the tank (A Bio Wheel 200 and a Tetra 20i) plus a 3 inch air stone. She would gulp air while the other fish not at all.

Something else I've noticed. She has flat back spots on her. Not ALL over. One on each gill cover and couple on the dorsal fin. Also a couple on her sides which I thought were from her diving toward the bottom then crashing into it. She doesn't appear to be 'scratching' or anything so I don't know.

The black spots could possibly be healing from some previous water problems. What was your PH reading by chance? As for the gulping air at the top,Can you try and take a look at her gills? Are they like a red,meaty color,or are you seeing kind of pale/tattered,spotted looking gills? If she's diving towards the bottom into the gravel,that could be a sign of flashing/scratching. What are the tank temps?

How are things going?