One method i've used in the past is to soak the pellets in your fish's favorite food before feeding...
So lets say for example your fish loves bloodworms only, then what you would do is take a few pellets and let them sit in the bloodworm juices for a little while (not so long that they just mush up and fall apart), then try dropping it in your tank and see if the fish take the bait...
IF at first they don't eat it, don't fret (but don't give up and feed them their regular food either), and try again the next day... keep doing this for about say a week and see if you can get them to eat the pellets...
Once they do start taking the pellets, then you can soak the pellets less and less each time in the juices of their favorite food until your feeding them pellets straight without soaking...
All in all, its about knowing your fish, they shouldn't technically starve themselves to death, but if after a week they still won't take the pellets, then its up to you if you want to keep starving them in hopes they take it (if they are healthy enough to do so) or if you just want to keep feeding them their favorite food and be done with it...
Hope that helps...