turtle ..aggressive now...

Question
I have a juvenile red eared slider about 1 1/2 yrs. old...introduced a FL slider
in March...bigger than the juvenile one..they got along well for quite a while.  
Now the little one is biting and nipping at the shell of the larger one.  The pet
store told me it may be a problem with puberty or male becoming aggressive
at this time, for a while.  Separate them for a few weeks and reintroduce to
see if that helps.  I did that, several times..and within a few hrs., the little one
gets aggressive again.  Perhaps the larger one is female and smaller one
male...Suggestions..I really don't want to do 2 tanks of turtles and the smaller
one by himself...seems to eat less now...thoughts???

Answer
I agree with the people at the pet store.  He may also be territorial.  I don't know if you've heard this before but many animals, especially ones that live in herds, have males that we refer to as the alpha male, the dominant male.  They tend to be very bossy and do like to prove their dominance.  That may also be the case.