Fishing got a massive overhaul starting in Reforged 6.2.1, and got further developed ever since. Fishing can now be used in both Lava and Water to fish up a multitude of pokemon and items. There are 3 kinds of Pixelmon rods in the game: Old Rod, Good Rod and Super Rod. The better the rod gets, the better the mons and items will be. There are mons that are exclusive to certain biomes, as there are other factors that affect chances too, like time and weather. Pokemon will be listes on the appropriate rod pages, with their biomes, rarities and conditions.
Items were also made fishable in 6.3, in both water and lava. Some are just the items of each type, like the Elemental Stones and their shards, the weather increasing rocks and the Elemental Gems, but some more specific items were also added. We also followed vanilla Minecraft tradition and added in vanilla fish as well.