I bought a 140 gal tank at the beginning of the year for my Asian RTC. He was outgrowing his 55 gal, so he needed a new place. I cycled the tank, and moved the fish in. After a batch of bad feeder fish, I thought I saw ich on his fins. Hearing the old wives tale, I threw 3-5 pennies in the tank in hopes to cure it. It worked. I later got rid of the fish due to its nasty temperment. I got a couple of koi from petsmart, 3 inches in length. I later bought a grass carp about eight inches. They were fairly active except for one koi. He would hide under a log, but grab a few bites during feeding time then hide. This was very unusual behavior for a koi fish. Two weeks after he showed this bizarre behavior, he died. Now my grass carp is doing the same thing. All my fish fairly frequently rub their sides on the substrate. I tested the tank for ammonia, nitrites, and nitrates to find absolutely nothing for either category. All I could think of are the pennies I left in there. I took them out, but now how do I detoxify the tank? The pennies were in there for probably a little over a month. I didn't really test for any other diseases. The fish all have no ich on them. Any input would be greatly appreciated. This is also not a permanent home for these fish. I am putting them in a pond I am making. I just want them to survive for a couple more months in the tank.
