Do you know where I can get a length weight table. I have tried Google but, only get American stuff...and thanks for the replies.
I got the girth bit wrong, I did mean depth, I have only been fishing for 40 years so, plenty to learn ..
I measured the roach from mouth to tip of tail so, got that wrong as well but, I guess the bigger fish was about 12/13 inches from the fork to mouth.
I guessed they were around a pound but, have never weighed fish, I just judge from average size of water fished; small fish, average fish, good fish, very good fish sort of thing. Having caught these two very good roach I thought I aught to start estimating the weight of some of the fish I catch and maybe weighing them if they are very good fish.