Green cory catfish acting very strange

[ABee]

Hello,

My green cory catfish (Who I have had for about a week) is acting really weird. He is just swimming around the tank vertically (Nose down, tail up). His right fin seems to be in tact, but it is not moving. A fish I just added to the tank had ich, so I returned him to the store, but my fish were exposed (no quarantine tank ). I added Ich medication (Super Ick Cure - by API) two days ago and then today (only 1/2 dose) per the instructions. Could the medication have caused illness? If not, anyone have any information on what the green cory is doing and why he is behaving so badly?

Thanks!!

 

[ABee]

More info. I only have an ammonia test kit, so ammonia is between a 1 and 2 - this is kind of a new tank. My previous one cracked, so I had to set up an emergency tank fast! Plants are old, but everything else is new.

The other fish I own are 2 other corys, 2 murray river rainbows, 3 african dwarf frogs, 4 ghost shrimp and one silver loach. I have a 20 gallon.

When I added the cory, I acclimated for about 20 to 30 minutes, then slowly added water to his bag from the pet shop until finally adding him to the tank without adding the water.