NEED HELP

hi i have two staffies one 8 years old and one 10 1/2 months in the past 3 weeks they have started to fight over things like just crumb of food on the floor or over toys. but the thing is the young one bites and wont let go. i have to force is mouth off the other. any advice would help thanks

I take it this is Jock?
Has he been neutered? How do you deal with the situation?

we have the plastic bottle with stones in. if they start to get a bit too boisterous and biting each other we give it a little shake. not a lot so as to frighten them just enough so they hear it and stop what theyre doing then they can be parted if necessary or just told to go to bed or behave.

Not a good situation and not fair on the dogs you need to think long and hard how your going to deal with this hope you get something
Total re think of everything that sets them off or potential of setting them off