Although a cup of butter somewhat defeats the purpose of eating lower calorie fish.
[Edited a few hours later: the recipe only calls for 1/4 Cup of butter. Lord knows what the brain cell that wrote "a cup of butter" was drinking.]
A hint that works: I'll ask specifically for a 2" thick fillet and then slice it in half at home. Usually the stores only have 1" slices pre-cut. This guarantees fresh-cut edges, especially if you don't know how long the pre-cuts were in the case.
Link:
http://www.finerkitchens.com/swap/forum11/21_Jimmy_Williams_Fish_Baste