I'm not really sure. You'll have to research more info on that. My first two were picked randomly and they are very healthy. The next four came from same place and all are healthy, although a little overweight! I just rescued one from a pet store that had him in a tank with cichlids! Poor thing was being nipped at. He was super skinny and looked stressed out. Now he is happy, getting bigger and much stronger. Basically if their skin looks normal and their eyes are clear, i'd say they are healthy.
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