Turtle Pet

I Have 3 turtles as pets! i love they.
I like the way they swimm like fishes haha! but wierd, i dindn{t know that the turtles can swim that way but I recently found it on internet. I also find that per every LITTLE turtle, your tank has to have as minummun 10 Litters.

I have 3 turtles now, but I don´t know if they are male or female so I can't name any turtle :(
I read that you can know the sex of a turtle only when they are grown....