Dollars swimming upside down!

[FINWHIPPED]

My dollars are swimming upside down. I also noted their stomachs are flattened (squared off??). It seems if they can't stay below the surface.
I moved them to a quarintine tank and treated them for swimbladder disorders. Kept the tank covered and repeated the treatment after 24h. 4 of the affected seem to be doing better but 2 still floats at the surface and struggle to swim down. What can be wrong??

[jeffs99dime]

what are your water parameters?

[FINWHIPPED]

Ammonia 0, nitrite 0, nitrate 30 for the tank they usually reside in (63gal). All the other fish seem OK. They all keeled over in unison after a fed them!!

Weekly water changes 10-15%, more than enough filtration.

[cocoa_pleco]

nitrates are a tad high. How old are they? any tankmates?

[Lady Hobbs]

Nitrates are too high and should not be over 20 max and closer to 10. You need to do a water change. Dollars also like lots of veggies. It's their main diet so start giving more romane lettuce, fresh spinach, zucchini and the like. I boil my zucchini about 3 minutes which will help it sink.

About an hour ago I was messing around outside and found a small earthworm. I always hear how angels gobble these things up so dropped it in my tank. Stupid angels swam around looking at it but wouldn't go near it. All of a sudden here come one of my Dollars. He grabbed that worm in a heartbeat and was tearing around the tank with it hanging from his mouth and 5 more Dollars were right behind him trying to get some of the action. It was pretty cute.

[FINWHIPPED]

The dollars are still young (1,5 - 2 inches). How old I'm not sure as I got them from the LFS after I sold my 4 big ones (4 -5 inches) for a handsome amount. In the tank with 4 angels, 2 cories, 2 mollies, a pleco and a black ghost. They are doing fine in quarintine tank and started feeding this evening as if nothing was wrong.
The four I sold went crazy for bloodworms and brine shrimp. They were not crazy for the veggie mix (lettuce, spinach etc.) but always were a pleasure to watch feeding.
How long must I leave them in the quarintine tank if it was ammonia piosining, or if it was something affecting their swimbladders (which I now seriously doubt)?

[Lady Hobbs]

Problem with some fish is they get too much meat products and will then turn up their noses at flake foods and veggies and spirulina flakes. Too much meat products is not good for them and should be given as treats ....unless they are mainly eat meating fish. Silver Dollars are vegetable eats and their digestive track needs the veggies. Too much meat can cause constipation.

Once they get used to some lettuce (romane not iceberg) held down by a rock, they will wipe it out within an hour of being there. They don't eat it from the top of the tank if it's floating.

Too much ammonia will cause top swimming and gasping so I don't know if it was due to ammonia but the nitrates are too high so it could be due to that. They can go back in the tank as soon as they recover.