That's great!
I sometimes measure fish for length. I used to weigh some as well, but haven't done so as much in recent years. I haven't weighed many carp, but I did weigh this one on a handheld digital scale. Its not my biggest on a fly, but thought it might help you estimate the weight on yours if you are so inclined.
27.5", 8lb 10oz.
I've tried measuring fish in photos, and scaling off something else in the picture of known size, and discovered it usually works out REALLY close. In most cases, fingers are visible and are right ON the fish. The last segment of the average human's index and middle fingers are approximately 1" long. Based on that, I estimate your carp was @ 26.67" long...so, not far off from the one I measured and weighed above.
David Merical
St. Louis, MO