Not being able to swim properly points towards swim bladder disorder. The ammonia and nitrites are consumed by the bacteria in your filter, which convert it into nitrates. A large partial water change (PWC) is what you need to remove nitrates. Never, NEVER, buy chemicals to remove something, which can be fixed by a PWC. Also, never add chemicals (i.e. medicine, chlorine remover, ammonia remover, etc. more info in P.S.) directly to the tank. Always dissolve them in a tumbler full of tank water (not fresh tap water, but water which has been in the tank for a significant time), and then add this solution slowly to the tank.
If your fish is still swimming weirdly, perform a large PWC, of about 60-70%, and add fresh water not treated with any chemicals, i.e. no chemicals added by YOU. Chlorine remover is ok, if it is added to the bucket, a couple of hours before the water goes into the tank. You can do without the chlorine remover, by filling water in a bucket(s) and letting it stand uncovered for the night.
Simple lines to keep fish happy:
- Always acclimatize them by changing their environment and their
surroundings slowly. Thus even PWCs have to be slow enough.
- No chemicals to be added to the tank, except when medicating them.
Chemicals should be added outside, to aged tank water only. Never
use chemicals to jump start your aquarium. Some beneficial bacteria
are good, but naturally establishing bacteria in your filter is
- Do unto your pets, only what your would do to yourself.
Meaning, you wouldn't use some chemical to clean your dog's messy
kennel, or your kid's messy rooms, would you?
My points are only to guide you out of this situation, and I really really hope that your fish survive.
P.S.: editing to explain what chemicals mean. Chemicals basically mean any compound or mixture of compounds which you add to the tank water, but which normally do not occur in the tank water. This includes medicines, rock salt, algae removing agents, beneficial bacteria mixture, etc. If any such chemical needs to be added for whatever reason, you should first mix it properly in a container (tumbler, bucket or bowl) of aged tank water, and then, this can be slowly added to the tank water.