as far as i have heard...you are only supposed to feed your turtle the amount of food that would fit in his head (not sure about the neck)... my one turtle is about 2 inches long, and i feed him about 3 pellets every other day with greens offered everyday! you also have to remember to vary their diet! they like to eat feeder fish, earthworms, chicken... but it definitely sounds like you are overfeeding your turtle! i have heard that the babies dont need fed everyday, only every other day! but i definitely offer greens and sometimes pieces of carrot everyday! they also need calcium... i do this by getting a cuttle bone from the pet store (for birds) break off the hard backing, break the inner part into pieces... and put a few pieces in once a week or so... usually i judge this by whenever the pieces disappear. sometimes they eat it, and sometimes they leave it go, but the good thing is that it dissolves in the water, so they are also getting calcium that way if they leave it dissolve! sorry.... didnt mean for this to be a book! hope this helps....
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~ Evie 
Pets:
German Shephard {Dusty}
German Shephard/Collie mix {Shadoe}
2 RES turtles {Booger and Snot}
African Clawed Frog {Bingo}
Snail {Gary}