Why do bass players tape their fingers?
Finger tape can be wrapped around your fingertips to protect them while playing. A pair of gloves can also help protect your fingers while playing.
How do I prevent blisters on my fingers from Bass?
The new skin will form pretty quickly under the blister if you leave it alone. Oh and the best way to prevent them is to just keep playing as much as possible and build up your calluses. You will still get blisters occasionally but they will become less frequent. You could also try flats or wraps.