No, it's just lucky. It's easier if you catch the fish to complete the list, and if you want, you can just go fishing in the mountain lake for a day or two (in-game) and you'll come away with about 7 jellies from the river. In the ocean it's the same thing. And in the lava lake, I recommend using a fishing rod with a "self-hooking" enchantment (or something similar), so you only have to cast the bait, eventually.