It really depends on what your Yellow Scrips are. I usually won't go Fishing for Yellow Scrips unless I have Thousandfang as my collectible, you can net quite a few of those in a short span of time and get some Mitsruki Sharks while you're at it for Red Scrips. I've fished a few Deemster's which aren't bad, and I've also caught Ala Mhigan Ribbon Fish quite a bit but those are the worst. Ala Mhigan Ribbon Fish require a Precision Hookset and they still get away from time to time, you also don't want to fish for them during Clear or Fair weather since you'll be adding another Fish to the hook list to compete against.