wow you guys are great

i love my garters they are so different from other snakes, they are lightening fast and have a Big personality.
im currently feeding them pinky mice, is that ok? its what they were being fed when i bought them but ive been reading that a lot of garter keepers feed them fish and now know its something they eat in the wild.
how often should i feed them? they are opportunistic feeders, ive been reading, so does that mean they will eat whenever food is available?
dont want to over feed them and make them ill :S
thanks for all your help