hi
no real way to tell a turts age and hard to sex a young one so you'll just have to wait

my guess is he is a young one pet stores get em in bunches,a very old turt can be small if kept in an unhealthy "dish" for years. but my guess is the pet stores get em young and try to sell em fast. one thing to note is that a turtle in a new place will tend not to eat, mine waited 4 days b 4 she did so please keep introducing the pellets veggies cuttle bone etc. krill is really not a healthy diet more of an occasional treat when the little guy gets hungry enuff and nothing else is offered he will fold in and nip other things if you stand firm. glad u figured out the stickys nutrition is one of em the dos and don'ts and amount,most of us like to feed in seperate containers than their tank, this helps keep the water cleaner (floating romain lettuce in tanks good)it also allows you to see what he ate. my turt still will not eat with me in the room. I leave her to her self for like 30 min. and all the pellets or what ever is gone,other wise she will just set their for hours touching nothing if I refuse to go away turtles are funny and each is diffrent in nature but we gotta b the boss about the diet.

good luck and keep pushing the good foods with in a week you will get rewarded unless they are sick they will eat soon.