So my 4 suggestions are mostly focused at big fish

1) A more controlled way of triggering big fish conditions. Some way to more consistantly trigger a big fish spawn than spend half-a-dozen or more windows up to chance. Maybe some rework to surface slap would help a long way here.

2) Allow a higher chance of landing a big fish based on either your gathering or perception stats. Working on ARR fish, having landed a big fish, only it gets away sucks, especially if you out-gear the area by 3 expansions worth of gear. I'm just saying to allow you to more easily capture fish if you out-gear it's fishing hole.

3) Allow Mooched fish to be surface slapped. There are quite a few big fish that are tied to a mooched fish; who share the same base fish.

4) Adjust the cost of abilities. Some of these abilities are way too expensive. Particularly Patient, Patient II, Precision and Powerful Hookshot. In areas that require a mooch, these get REALLY expensive on the GP. Combine that with Surface Slap, and you are just chugging Cordials on cooldown.