what do you use scales for?

You use scales to buy things in the scale shop

You can buy pets (the more scales they cost, the more genetic traits they'll have),
lesser mutators (add random visible/carried genetic traits to a tamed pet),
lesser dyes (change the colour of your pet)
lesser philters (increases stat of pet when used on hatching eggs)
philters of unlearning/learning (to stop a pet from gaining exp/to reverse the former's effect)

In the future, there may be more things added into the scale shop that is buyable with scales. =)

okkaythank you!

you're welcome. =)