LOL, I feel sorry for those of you way up north! My fish have been up and eagerly feeding for almost a month now. Actually witnessed the first Goldfish trying to spawn yesterday morning. may have been a good spawn as they clouded up the water pretty good yesterday. I'm not intrested in raising comets/shubunkins this year so if they live they live if they don't oh well. I'm waiting for the Koi to start which should start next month, Then I'll be trying to recover SOME of their eggs. I ended up with 13 babies last year which of those I kept the three gin rins. Year before that I ended up with 19 koi and 250+ goldfish. I still have two of my first koi offspring also. Traded off all the baby goldfish as I didn't have the room to raise them.
As for your question, Fish will usually start trying to feed at about 40-45 degrees. They really should not be feed at that temp as they can't digest as well. If your going to feed from 45-55 degrees I recommend feeding wheat germ and then feeding only very lightly when they are up looking, DON"T feed hoping they will come up!. Waiting until 55 allows the fish to be more active and eager to eat and they can digest the food at a more constant rate allowing for better growth and nutrition over feeding when it is cold as the fish will eat but can bloat as the food simply does not digest correctly.
Imagine eating a box of cereal, Yes a whole box! Not throw in a pound of cheese NO not halfa pound a full 1 pound block!, drink a gallon of water. NOW, Don't go potty for the next week! UGH, horrible thought huh? But in reality that's what feeding your fish early can and will do. they won't starve, If they aren't eagerly eating, let nature take it's course.