I like the way he says this is the first time they've...

I like the way he says this is the first time they've encountered the problem, then a minute later admits it has been going on for 1-2 years, but the bacteria has not cause major problems until recently.

My experience in animal production is that often a disease pops up, the scientists/vets try to identify it, they find something, and say "Ah huh! Found the problem!" when really they've just found another thing which is always there, or sometimes even supposed to be there, and mistakenly attribute the problem to it. The number of idiotic judgements I've seen vets make over the years is astounding.

If the fish have had this bacteria for years but it is only recently that they have had big mortalities and growth retardation, I would suggest it's possible there is another disease at work and they're focusing their attention on something which isn't all that harmful. Alternatively and quite likely, the story isn't being delivered fully or accurately to us.