I have a couple things I would like opinions on.
1. Is wasting disease (fish becoming very skinny ect) most likely caused by a bacteria or a parasite?
2. What would be the best line of treatment for said disease?
3. Is this disease contagious to the other fish in the tank?
4. Can this disease cause fish death?

I have a few species of fish that seem to get this one right after another.
If you have any input or ideas on the matter, I would greatly appreciate your comments.