To get a Goldfish Bowl with a fish, you need to take an empty goldfish bowl underwater (Calassa - passage from Captain Max, Liberty Bay, Sunken Quarter in Yalahar, Frozen Trench on Tyrsung and Sea Serpent Area - passage from Captain Haba, Svargrond), and "use" it on a patch of coral or seaweed with a fish swimming in it. After you used the empty bowl on the fish you will have a goldfish inside the goldfish bowl. This is how the fish looks like:

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