Dexter Russell makes good inexpensive knives. I used to use the hi-carbon boning knives. My favorite was the 6" but they range from 5-8 inch blades. (model #s 1375 1376 1377 and 1378) I don't like a thin, flexible filet knife for cutting fish (and I've cut a LOT of fish in my day), except for small flatfish like the gray sole maybe. They are inexpensive knives, and if you rinse them when you're finished and throw some olive oil on the blade, they'll last years. They take a razor edge very easily, hold it well, a few passes on a steel restore it in no time, and resharpen nicely when necessary.