Knowing your fishing level would help, but since you have your Lu, I am assuming you are at least 55+. While north Qufim is a good money making spot and can be good for skills, it has a streaky bite rate at best and takes a skill 0f 70+ to catch anything with consistancy. The two main fish you target there are the Gigant squid and Black Sole which both cap in the 90's and take a high 70 low 80's fishing skill to catch with any thought towards gil and decent skill up.
If you are in the 55-65 range, then main job whm or sub whm and head to SSG. Level 60+ jobs wont get agro around the lake and you can catch bream, grimmonites and nebimonites with decent skill off the grimms and breams. You also have the occasional coral fragment thrown in that sells for 10k or so. Also, IMHO it is not nearly as streaky as Qufim. I have spent the last couple weeks here and went from 71-77 fishing and am enjoying it immensely.
Either way, congrats on your Lu and enjoy. I know it was hard work to get. ^^