They will be able to swim for the rest of their lives... I keep mine in rubbermaid tubs with moistened paper towels for a substrate as soon as they change from waterdogs though. If you don't separate them make sure the salamanders have a haul out area like a floating piece of bark or something like that. Once they have all changed to salamanders I would set them up in your mostly land tank.

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0.1.0 Colombian Red-tailed Boa (100% Het. for albino)
0.0.2 Western Hognose Snakes
0.2.1 Plains Garter Snakes
1.0.0 Red-sided Garter Snake
1.2.0 Barred Tiger Salamanders
0.0.1 Red-eared Slider
0.0.1 Common Snapping Turtle