My 6 month old chocolate lab has stopped playing fetch. He used to love playing but now he won't hardly go after the toy. He now only goes about 15-20' then turns around and comes back to my side. I've tried several toys wondering if it was a disinterest in a specific toy. No interest at all please help.

Don't throw it so far. Throw it half that distance and let him go get it, and slowly increase the distance. I wouldn't be too worried. I have a lab mix (we think chocolate lab and..?) and some days he couldn't care any less about toys. He just wants to be with you, other days he is ready to go and wants to play fetch for hours.
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I have two dogs and both of them love a toy called a flying squirrel. It is sort of like a frisbee only square. It also has curves in the side so when you throw it and it lays flat on the ground that the edges have a curve in it so it isn't flat on the ground and the dogs have an easier time picking it up. It also has some glow in the dark things on it so you can use it at night.

That is very strange for a Lab, labs tend to get more energy the more they run and walk. I wonder if you should call your vet/vet tech and talk to them. When you have a change in your puppies/dogs behavior, it is always good to call your vet. It might just be that the puppy is bored with the game, but since you said it is a lab, and it takes tons to wear down a lab, I would think the best thing to do is call your vet. Good luck.

it might just be the toy...
you never really know with puppy's..
try using a stick or getting him something new.. pets question and answers,www.5d2d.com

they're kind of like children in the sense that they become tired of things (out grow) things quite rapidly...

try a KONG.. my dog has had hers since she was a puppy (she's 11 now) and she still loves it.. its one of the few...