Generally, for goldfish, you need 10 gallons per fancy goldfish. So in a 44g, I would say that you could keep 4 fancies.
I keep GFs. One thing that you need to keep track of, is the types that you combine. If, say, you put more-awkwardly-shaped ones in with comets/commons, the rounder fish might have trouble getting enough food. I do not like to combine comets and fancys, but I do have one comet in with my orandas. They seen to be doing fine..
GFs are messy fish! Frequent water changes are needed.. over-filtration works for me.
Gees, i could talk GF all day. Do you have any specific questions?