Over the course of my time on PF, I've been an avid fisher. Based on what I've heard in regards to how the fish are determined, and based on personal experience, I don’t think that the current calculations that run are fair for everyone. Below will be how I view the process for a custom fish being chosen should be (I am not familiar with how it currently works, so some of this may already be how the code works). My proposal for how the fish you receive should start with determining the rarity. This is already done within the code that has been created, whether through the weight system Minecraft uses, and RNG value being rolled, or another alternative. Next up, the fish to be given will be rolled/chosen based on the chance for each specific fish in that rarity bracket. I'm assuming that for all but the mythical fish this is an evenly split chance. Once the fish is chosen, the size can be generated based on the range of possible values for that species of fish. Now how does this differ from what happens right now? It appears that the order is Size to Category to Fish or Category to Size to Fish. Either way the size carries too much weight. While the mythicals are supposed to have set chances of being caught, that does not seem true. For example, lets say that the chance for the trio of mythicals is 40% Jellyfish, 35% Turtle, and 25% Axolotl (I have no clue I'm just providing an example). Over the course of this event you catch 10 mythicals; that's pretty lucky. You would expect 3-5 jellyfish, 3-4 turtle, and 2-3 axolotls, but chance will play into how lucky/unlucky you get. From my experience, even if there is supposed to be certain chances for each fish, it cannot apply if the size is determined first. Example: lets say you catch a fish. It generates a size of 900cm. When it pulls from the mythical pull, there is only 1 fish that it can be, and will ignore the other 2 completely, acting as if its a 0% chance for the jellyfish, 0% chance for the turtle, and a 100% chance for the axolotl. If the fish were determined first, the ratio of jellyfish, turtles, axolotls would be much closer to an expected value with axolotl being rarer than the other two, not (based on my catches) the axolotl being more common than the other two. The majority of the fish I have caught is with a Bait enchanted rod. Bait increases the size of fish caught. Currently, if I'm correct in understanding how the process works, increasing the average size completely skews the chances toward larger fish, giving (possibly) unintended better odds of the larger fish to those with Bait. It should only affect size, and not have a role in determining fish species. Reconfiguring the order of elements in creating the caught fish would keep the playing field level for all who wish to partake in custom fishing and keep the benefits of this custom enchant from manipulating the chances from what is set, or at least should be set.