Found those informations when googling : "Various methods including float, ledger or feeder are used to catch eels. Float fishing with a waggler over a bed of groundbait, slightly over depth close to reeds is a good tactic. The feeder is also considered a good method." and "Lay a bed of groundbait using brown crumb or continental groundbait with your old bait, maggots, casters and chopped up worms mixed in." Also "This comprised of some mashed up dog food, molasses's, sprats and some anchovy & sardine dynamite baits additive."
Time to see if the rf4 dev used those information into the game.