First, you roll the dice for the rarity of fish; then you get a random selection of available fish of that rarity in that region; then you roll the dice for the size of that fish (if not fixed).Fishing luck will increase the chance of getting more higher rarity fish. Fish size perks will increase the average size of your fish (with all size perks maxed, you rarely get small fish at all). Fish size perks have no effect on fish that have no different sizes (e.g., clams, snails, etc).We all know that bigger fish will give more salvage. So if you're e.g., fishing sturgeons for fish roe, you will most likely want to maximize size first and only then see how much luck you need to catch the most sturgeons (e.g., you would want 0 luck if you fish in a secret hotspot, but as much as you can get if not in hotspot).While if you fish for pearls or legendary fish, then you don't care about size at all, as clams and legendary fish are fixed size.Besides, you should know these:1) what minimum roll you'll need for desired rarity of fish. 2) how much luck does each hotspot gives. 3) the odds of getting different fish with given luck applied and find the maximum.Too much luck is only a real issue for secret hotspots. E.g., with max luck, you would be getting only treasures and legendary fish and selling them for more New World Coins. If you're looking to catch rare fish there (e.g., getting pearls in reekwater would be much more profitable, than useless treasures or low-value legendary fish), then you want lower luck (but not minimum, since there's still a chance to get greens; in that particular case, you want to minimize green/treasure/legendary and maximize blue).If you specifically want white fish (well I can't think of a reason, but there one day maybe), then any luck anywhere is bad. If you want boots or other junk, then you definitely don't want any luck at all.For any non-white rarity outside of secret hotspots: more luck is always better. Legendary in secret - max luck, treasure or blue in secret - optimize, green in secret - 0 luck (although a rare hotspot with luck would simply be overall better for green fish than 0 luck secret).There were some videos made about fishing luck with exact numbers and examples, so just find those if you want to know more.
