Fractions aren't needed in the metric system, e.g. 250g is 250g, 982g is 982g, 72cm is 72cm, 1.6m is 1.6m etc. I was schooled for the most part in the imperial system but we went metric in 1967.
I like to call my trout in pounds out of habit and a lot of us older guys still do. Besides an 8lb rainbow sounds bigger than a 3.628 kgs rainbow.