I started my 6 month old on solids yesterday bananas and today he pooped green eith like mucus and a little tint of red is this normal?

Baby poop: yes not abnormal. The shape and color will continually change based on what you are feeding him. Good luck

Yes: It can be. Anything that introduces something new to the gut has the potential to change how the poop looks. Bananas have been known to turn the poop black and /or green. The red is a bit odd, and obviously if there is more red coming, then a call to the doctor is a good idea. Few are allergic to bananas but it is possible.