[i have crabs]

Finding an egg shouldn't be too hard, I bought. 1 from golds and 1 from Pisces before, I'd recommend doing it that way, I have a bamboo that's 2 years old and about 18" 6' long is ok but 2' wide is the minimum I'd recommend,they need the width to turn around,they don't swim a lot so your tank will be fine for quite a while aslong as its not crammed full of rocks but in the future a wider tank like 30-36" wide would be a lot better, buying an egg will also cost you half the ammount a hatched one will cost