I have a book by David E. Boruchowitz called the simple guide to freshwater aquariums
http://www.petworldshop.com/tfh/the-simple-guide-freshwater-aquariums.php
I have found that this book is well worth the investment for any hobbyist
It explains everything in an interesting and captivating manner (If I could write like him I'd be aceing my writing class)
As for the betts you may have picked out an old one or one of weak stock
Most breeders sell off their "less than perfect bettas" after they grow out their fins
That there is already a decent chunk of their lifespan and considering the pressures of pre purchase life this betta if yours may just be glad to end his short life in comfort
Sorry if I seem less than optimistic but this is part of the hobby all of us must deal with
http://www.petworldshop.com/tfh/the-simple-guide-freshwater-aquariums.php

I have found that this book is well worth the investment for any hobbyist
It explains everything in an interesting and captivating manner (If I could write like him I'd be aceing my writing class)
As for the betts you may have picked out an old one or one of weak stock
Most breeders sell off their "less than perfect bettas" after they grow out their fins
That there is already a decent chunk of their lifespan and considering the pressures of pre purchase life this betta if yours may just be glad to end his short life in comfort
Sorry if I seem less than optimistic but this is part of the hobby all of us must deal with