and is the fungus and colomnaris contagious? will it go to other fish in the tank?
It can, but it usually just attacks the fish that are stressed and in poor condition. Thats why the feeders being kept in poor condition were starting to succumb to it. Healthy fish in good quality water should be able to shrug it off.
The fungus and bacteria spores are all around us and in the tank water, just waiting to come across a host with a poor immune system. But why tempt fate by dumping an extra dose of them in along with a sick fish
Bury them in the backyard or throw them out in the trash - safer than taking a chance with your fish.
Cheers
Ian