Give him some time to heal. Exactly how high was his ammonia? I have had fish from petco that have had ammonia levels so high, it turned the test water BLUE
and a few others that had tested at 8.0
They are pretty hardy fish but it depends alot on water chemistry. i think a higher PH makes ammonia more lethal then it would be at a lower ph, or maybe its vice versa. I dont remember which way it is.
If the level was high, he may have ammonia poisioning:
- Fish gasp for breath at the water surface
- Purple or red gills
- Fish is lethargic
- Loss of appetite
- Fish lays at the bottom of the tank
- Red streaking on the fins or body
Ammonia poisoning can happen suddenly, or over a period of days. Initially the fish may be seen gasping at the surface for air. The gills
will begin to turn red or lilac in color, and may appear to be bleeding. The fish will being to lose its appetite and become increasingly lethargic. In some cases fish may be observed laying at the bottom of the tank with clamped fins.
As the damage from the ammonia poisoning continues, the tissues will be damaged as evidenced by red streaks or bloody patches that appear on the body and fins. Internal damage is occurring to the brain, organs, and central nervous system. The fish begins to hemorrhage internally and externally, and eventually dies.
Do you notice any of these symptoms? or any other things like white fuzz, white dots, stringy white poop...
If it is caused by ammonia- he may just need time to heal a bit. Usually clean, warm, conditioned water is all it takes.
Also is your tank filtered or unfiltered? In order to keep ammonia levels down, you need to do a water change at least once a week. For tanks that are cycled - you only need to do a small water change each week. If its unfiltered you should do a 100% change with gravel cleaning and a smaller 50% once a week.