About that multiple feeding a day, their is a time interval between each feeding for you to gain an increase of Aquarium's Overall Health and, I guess, Fish's Happiness.
Although you can feed them again and again by refreshing the Aquarium page, you won't gain any increase in Overall Health or Fish's Happiness (maybe) in the second feeding, the third and so on.
Like I said, you should wait for the fish/es to get angry again, I mean, hungry.
Don't ask me how long should you wait for to feed them again because I don't know too. ._.'
Try experimenting for the time interval by:
Feeding them with an interval of 2 hours (or so) and taking note of the Aquarium's Overall Health if it increases. Do this for two days or more.
Then after two days, increase the hour interval by an hour or 2 and still take note of the Aquarium's Overall Health for another two days.
Repeat the process until you determine an approximate time.
Note: You should wait for the popping hearts or maybe refreshing the page to see the increase in the Overall Health, if there is any.
Also, I don't know how/when does the Fish's Happiness increase. Although they increase more with multiple feeding.
Like 16 Happiness/day with Feeding Once everyday.
And 48 (more or less) Happiness/day with Feeding more than once everyday.
And make sure you have the correct Light/Music/Temp for your fish.
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My Overseer gave me these items with much worth:
Elegant Black Satin Coat (56k / 28k if sold in store)
Fluff Box (~36k when I got them / ~22k now)
And other many items that I didn't know they exist.
It never gave me a Fairy Wing.
stare (Although my mules each got one)