Will Sick Fish..., create greenwater? Options

[d_golem]

I got a QT tub that's housing a small sakura ranchu right now. It's located outside and is partialy shaded so it got sunlight about 5 hours a day or so. In the last 2 days, the water is starting to turn green rapidly. I got an established greenwater tub myself, and I've read that to start a greenwater culture u must have healthy fish.
So does this mean that the sakura ranchu is healthy and no longer need to be QTed? He's in there about 3 weeks already.

Cheers