I think you could probably keep a pair of rams, but wouldn't keep any rainbows with them in a tank that small. Also, I don't think there are any rainbows that can be kept in a ten gallon tank (even without the rams) b/c they are a schooling fish (i.e.-at least 5) and need plenty of space to swim, as I have heard Roan (our resident rainbow expert) say in another thread. However I might be wrong about this, so someone feel free to correct me if this is the case.