Hi Flavio, Dwarf Burms don't come from Vietam. They are actually on an island in Indonesia. I only say this because there are some out there selling normal burms as dwarfs, so be careful. The size sounds about right though.
Dwarfs seem to be more difficult to breed. I'm not sure if it depends more on age than size, but 3 to 4 years old seems to be the right age for females. We are seeing a lot more action with our dwarfs this year as opposed to last year, nothing came of our breedings last year. They also don't breed as often as normal burms. Ours are only breeding evey week or two. We hope to produce some babies from ours this year.
Hope this helps.
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Randy and Michelle
Art In Scales
(719) 439-4199
info@artinscales.com