Doesn't matter all too much where you start, you'll feel for whether you want bigger or smaller. Deba sizes I have owned ... Uhhhh, 105mm, 120mm, 150mm, 165mm, 180mm, 210mm, 240mm (mioroshi and thinnish deba). As long as you can use it on fish that size, or poultry that size. I think @Greasylake...