Well, I'm stuck too, but apparently the food differs from game to game. Try a fly agaric
mushroom, a centipede and a globefish. If not, no idea, you could ask Youtube or
something.

why did you send me that *** message

thats mean to say that plus i didnt write that but i wrote this question.And its mean to
say that to someone.And the person under the question thanks for the info.Now i need to
find a globefish.

i am sooo bad at catching fish.So basically im doomed

Well, it worked for me!
I just started with giving him mushrooms.
It seemed alright, he was all like;
They make me laugh, but I get sleepy again, after..
When he's like that, it won't work.
You can try it for some time, and then
he will tell you if you have the good things
with you without you even need to try.
He asks for 5 different things.
I had a catfish, 2 centipede's (one big, one small),
and some mushrooms.
That was okay, he didn't ate it all, though.
He ate my centipede's and a mushroom or two.
That's when he went back to the castle, full of energy.

Thank you but do u need the catfish or is it just an option

You need a tiger globefish, a laughing Jin mushroom, a fly agarcic mushroom,a centipede
and that is all I know. You really do need these things. I've been stuck on this mystery
for AAAAGES, and I think you need a manragora root. Just a maybe.

Also, if you dunno how to catch fish, you cast out but not too far. Then you pull in a
little bit. (oh, there also has to be a fish there in the first place) If the fish ignores
you, keep pulling in but not so far that you pull out of the water. The fish should start
swimming towards you, and keep pulling in. Whan you get a bite, press X like CRAAAZY. If
the fish gets away, take out your line and go fish somewhwre else. Wow. I feel like a
guru. I should write a manual or something.