This project has moved to Planet Minecraft.
This data pack changes fishing such that you catch fish entities instead of items, and these fish entities will drop the usual fishing items in addition to the usual drops of that entity. There is also a 1% chance that you'll catch a drowned, which also gets the fishing treasure and trash in addition to the drowned loot table. The types of fish entities that can be caught are the same as the fish items that can be caught normally, and have the same chances of being caught as in the normal Minecraft fish loot table.
You have about twice the usual chance of getting trash or treasure from these entities when compared to normal fishing to make it worth the chase of killing them, but you'll need to be the one that kills them or they won't drop anything. Killing these entities with a weapon that has the Looting enchantment will increase the chance of receiving treasure, and decrease the chance of receiving trash.
These fish entities can be caught in buckets like every other fish entity, but are otherwise not persistent.
This data pack's loot tables do not dictate specific item drops from the summoned entities, but instead point to the normal Minecraft loot tables for that entity, fishing trash, and fishing treasure; therefore, if you've got a data pack that changes these loot tables it will also affect what loot you get from the entities you catch while fishing with Feisty Fishing installed.
More information about data packs and how to use them can be found on the official Minecraft Wiki.