chances are you had a bit of moss on your tube or something. It is very rare you catch a grass carp on a tube jig but can if there is moss on your tube. Local farm pond has 10-15 of these things that are close to 4 and 5 ft long and if i get moss on my jig they are a nuisance cause they will hammer my jig. I have caught 4 or 5 over the 6 years i have fished this particular pond.