I believe daily 100% water changes and aquarium salt added at 1tsp per gal maybe be a good start for healing from ammonia poisoning.
Just remember that using aquarium salt has a 10-day max medication session, so after 10 days of using aquarium salt after every water change, you'll have to give him a break from it before using it again.
But hopefully by the end of 10 days of usage, he'll be well on his way to recovering.
You might want to get a slightly larger tank than a half gallon along with a heater for it to use as a hospital/emergency tank and to keep the water around 80ºF along with ensuring that you add the correct amount of water conditioner to the water before putting the fish in it.
A 10gallon tank is a wonderful home but just because its large does not mean you don't have to do any water changes.
For an unfiltered 10g tank, you should be doing at least a 50% water change a week with a 100% water change at least once a month to clean everything of any slime or algae.
Always add water conditioner to the amount of water you're adding back in before you pour it in the tank.
If you get a filter for the 10g, you can reduce the 50% water change down to 25%, but would still need to do a 100% at least once a month to, again, keep everything clean of slime or algae.
Last edited by Luxavior; 11-04-2012 at 11:22 PM.