I killed FDR

We finally got the new filter cartridges for the tanks that we've needed for awhile. But, the new cartridges don't have the bacteria buildup that the tank needs initially, so we had a huge ammonia spike, especially in the top tank. All of the fish on top were gasping, so I moved T and Spike into the bottom tank with Zebedee temporarily. After a day, the ammonia went away in the top tank, but Franklin was so affected by it, that he could barely swim and needed to be flushed. Since Zebedee and Spike did not always get along, I moved Spike back into the top tank. All seem happy now. Except for Franklin; he seems dead.