Small questions about fishing.

[ISSsloth]

• Do things like perfect catches affect the length of the fish or is that random?
• How do treasure chest spawns work? Do they spawn completely randomly of at a specific time?
  • If it's the first answer, would purposely making the catch take longer raise your chances of getting a chest?

 

[Giant Octopodes]

1. Perfect catches do not, to my knowledge, as it's not listed and I've gotten longer fish from non-perfect catches than from perfect catches. However fishing zone and fishing skill level definitely do, it's not totally random. I'm no expert on that area though, all of that is just anecdotal and could be wrong.
2. There is a 15% chance of one spawning on a given catch (baseline). You can increase that via Magnet bait, the Treasure Hunter Lure, and the Pirate Profession, to get it as high as 50%. If it's going to spawn for a catch, it does so pretty soon, before the catch will finish even if it's a perfect catch, in my experience. If it's not going to spawn, it will never spawn. It doesn't sometimes spawn like a minute into a difficult catch for example.

 

[imnvs]

Perfect catches enable iridium quality fish before you can get a quality bobber.

 

[Lew Zealand]

Treasure Chest spawns are also dependent on Luck, both Daily Luck and anything you eat or wear to improve your Luck, in addition to Señor Octopodes' mentions. When making a choice between the Treasure Chest and an Iridium quality Fish from a perfect catch, I try to do both. And usually fail, so I go for the potential shiny things in the treasure chest:

Ooo more Bait. ftw...