The Fish Fin Manipulation is used to consistently gain Fish Fins in Fastitocalon-F encounters.
Normally, each Fastitocalon-F can drop between 0-3 fins (and thus the player can get 0-6 fins per encounter as they come in pairs). The manipulation results in a more consistent drop rate of 4-6 fins per encounter. Due to the 15 FPS battles on PC/HD versions, these manipulations see more usage on PSX/Digital versions where the battle FPS is 30.
The initial data to make these manipulations came from the Japanese speedrunner Pingval. He created a video and accompanying dataset with the 256 possible seeds for the Fastitocalon-F encounters on Balamb beach. He also made an example of how a the fight could be manipulated to achieve 6 Fish Fins in one encounter.
From this data, awesomeWaves began working on creating an RTA manipulation using the Quezacotl GF. Battle RNG would freeze for the animation of the summon, allowing the player to change the RNG (and subsequent drops) by refreshing the ATB. The manip consistently yields a minimum of 4 fins and has a 35% chance to drop 5+. The manipulation was created with the help from bodcap, Kiitoksia, Brofar and Thomas_8989. It was released for public use 11th of Dec 2021.
Shortly after on the 24th of January 2022, Kaivel completed work on his own version of a manipulation. This manipulation would use Quistis' Laser Eye limit and alter the RNG during the Thunder animations. While much more difficult to perform RTA, it is designed to always drop 5+ Fish Fins. As the manipulation also requires Quistis to be in limit range (critical HP) it has a lower success rate. However it is the fastest manipulation and has seen usage in the top runs on PSX versions.