Why is my dwarf gourami always so hungry?

I just got a male flame tail dwarf gourami yesterday. He was trying to eat his plant, and then also the fake pineapple (spongebob house) in his tank. Then he tried to eat the rocks at the bottom. I have fed him multiple times (tropical fish flakes) since yesterday. Why is he so hungry?
Why is my dwarf gourami always so hungry?
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