I started out with 7 in a 29 gal. They never bothered the other fish. I had one blue gourami with them and 7 skirt tetras. Then I moved the tigers and the skirts in my 75 gal with bait and tackle shop minnows, 2 giant danios, SAEs, a CAE, and 2 bristlenose plecos and at one time I also had some corys in the tank with them. My tigers have always behaved well. With 9 they will be busy chasing each other and you should be ok.
When you move them to the new tank I would move the tigers last, so the other fish can establish their territories first.
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