Rainbowfish Dying

I also posted in the Freshwater Fish Disease section, but didn't get much help, so I wanted to try the Rainbowfish section. After several months of successfully keeping BosemanI Rainbows with no deaths, I've had 5 deaths in about two weeks, with the majority coming in the past week. At first, it appeared that I had a fish with Cotton Wool disease, but that fish is still living, and is one of the more active fish in the tank. The ones that have died didn't have any physical symptoms other than the typical behavior of hanging at the top of the tank, and then dying a day or two later. It's not a water quality issue or an aggression issue (that I can tell), and no other fish in the tank, besides the Bosemanis are effected. I'm wondering if anyone knows of anything that could be specific to Rainbows causing this, or if this is literally a freak coincidence. Thanks in advance!

 

Put water conditioner in, then do a 50% water change.

 

I went and found your previous thread to get info on tank size, water parameters, previous treatments, etc. Did you google columnaris? It is odd that whatever this is seems to only affect the rainbows. Columnaris does not discriminate. I agree with coralbandit that this is most likely bacterial. The dying fish have no signs of injury. (fungus feeds on decaying matter) It is very difficult to tell what is going on without pictures. You did the entire round of kanamycin?

 

Put water conditioner in, then do a 50% water change.

Thanks for the recommendation, but since it's not a water quality issue, what's the goal of this? Just curious to understand why this is the recommendation.

 

I went and found your previous thread to get info on tank size, water parameters, previous treatments, etc. Did you google columnaris? It is odd that whatever this is seems to only affect the rainbows. Columnaris does not discriminate. I agree with coralbandit that this is most likely bacterial. The dying fish have no signs of injury. (fungus feeds on decaying matter) It is very difficult to tell what is going on without pictures. You did the entire round of kanamycin?

Thanks for the recommendation! So, do you think I'm incorrect in guessing it's cotton wool (I'm nearly certain it is), or are you suggesting I likely have two issues going on? I haven't Googled Columnaris, but I will, and I'm not using Kayamyacin, I'm treating with API Fungus Cure. I did the first dose on Friday night, and will be doing the second tonight.

 

Ugh! More death. I've been continuing to lose 1-2 fish per day, all (so far) Rainbows. So far, I've only lost Bosemanis, but today I have a Turquoise not looking great. This morning's dead BosemanI is showing what appears to be fin rot with a decaying tail. The Turquoise showing symptoms is showing a white/popped out eye. This is horrible!