How to match the arowana in Obi Island and how to match the dragon balls according to the specified method?

Hello, in the aquarium of Obi Island, arowana can be matched in a certain way. When you put two fish in the same fish tank (according to the specified method), it will become a yellow bead. Move the mouse up, and he will see a few words: How long do you need to hatch _ _ _ _ _ _ (the arowana you want to hatch) or 30 dragonball essence. If you must hatch successfully, you can use props to increase the success rate of hatching. So, even if you follow the specified method, you will get the essence of Dragon Ball. I think when you say Dragon Ball, you mean Dragon Ball Essence. ) I hope to adopt O (∩ _ ∩) O. Thank you.