I wouldn't call them unpredictable so much as nonchalant in their "hurting" of the hand that feeds them. My F1 yellow would calmly turn his head into me and give me a good slashing about once a year, despite me having worked with him a great deal since he was a nippy newborn. My F3 green never made me bleed. I considered both animals extremely tame. I'd feed larger meals every 2-3 weeks. Careful not to overfeed. There are already enough morbidly obese anacondas in captivity without adding more.
So if i handle a baby frequently and feed well, i'll have a happy anaconda? And what do you feed every 2-3 weeks?