Need Help with my tank!

[55GalAquarium]

I have had a 55 gal aquarium for about 6 years now and I have never had as many problems as I am having right now. We cycled when we set up the aquarium and it has been good for years now but now we are having problems with very high ammonia levels. A couple of our pictus catfish were getting sick so I put an antibiotic to treat, on the label it says it is safe to use and won't affect biological filtration(Maracyn-2). The past time I treated the fish, I did a 25% water change to clear the cloudiness and within a couple of days my ammonia levels were up to 8ppm. So this continued for 2 weeks and I tested again because my fish were not showing signs of stress up until then. Still at 4ppm, so I did a 50% water change the first day and have been doing a 25% water change for the rest of the week. It has been a week of doing water changes and I'm still reading at 4ppm. I bought Ammo-Chips that go in the filter. Does anybody know if these will remove the ammonia but it will still test positive. I'm pretty sure I still have a high ammonia level because my fish are all acting stressed and we lost a bala shark yesterday. We have 2 bala sharks left and 4 pictus catfish in a 55 gal aquarium. I don't know what else to do anymore, please help! I have been adding stress coat after doing the water changes but nothing else other than ammo-chips.

[Judge]

Sorry for the troubles. Need to figure out the cause of the ammonia. I am not an advocate of using any chemicals at all. Not sure about all the ones you have used and the possible consequences. I would keep doing water changes as often as needed to keep the ammonia in check. What are you feeding your fish and how often? What kind of filtration and how often do you change it? I know these are basic questions but, again, you need to find the source of the ammonia. From what you have stated, you are not overstocked. I also realize that you are not new to the hobby, if this tank has been going for 6 years with no problems. So maybe you should back track some to try and pinpoint when the problems began and anything new that could have sparked the problem. Please keep us up on what transpires...could possibly help others. Again, sorry for your problems.

[55GalAquarium]

I have had a Whisper Power Filter for a 60 Gal aquarium since we got the aquarium. I usually change the filters every couple of months. Haven't been good at the upkeep as far as regular maintenance but I do change the filters. When the catfish started getting sick I realized that I should be doing the maintenance more frequently. So I think this problem started when I put the medicine in. Again, the package says it does no harm to the biological filtration so don't understand why the ammonia levels spiked after using it. I've been feeding the fish 2-3 days for over a year now, they get flake food for the bala sharks and I have sinking shrimp pellets for the catfish since they are bottom feeders. Since the ammonia problem, I have fed them once last night but that was the first time in a week. Just don't know where this ammonia is coming from!