Beautiful fabrics! Do what appeals to you. If you are leaning towards the Asian large fish one but think it's too big for a mug rug, maybe a table topper, placemat or kitchen table runner would be nice. You could however use the fish on the length 10 X 6, that doesn't sound too big? Or you could do a mug rug in the fish and a couple of pot holders in the other fish print and have her choose. OR
Make her a pin cushion/thread catcher out of the smaller fish fabric, if she sews she would probably like one. There are some nice ones on posts on QB and they are simple to make.