Always keep in mind that all fish 4" long do not have the same size mouth. So if you want a good 'guesstiment' for pellet size a fishwill eat measure the width of the fish's eye. This width comes real close to the ideal hard pellet size for that fish. Fish can eat larger sized soft or hydrated pellets compared to hard dry pellets.
The following pellet size fish length chart is for LMB, SMB, YP and trout. As menetioned a larger fish can easily eat a smaller pellet.
http://aquamax.purinamills.com/aquamaxfishdiets.htmOne Pellet company's opinion and Cody modified: For LMB, SMB, YP, Trout - NOT BG & HBG
Pellet---------------Fish Size
2mm 3/32" ------------= 3"-5" fish
2.4 -2.7mm 1/8" -------= 4"-6"
2.8-3.2 mm 3/16" -------= 6"-8"
4 - 4.8 mm 1/4" ------- = 7"-10"
5 - 7.1 mm 5/16" -------= 9"-12"
