I am making a Japanese garden cake for a friend, and she wants a koi pond on it. But she wants to be able to see the koi fish under the "water" of the koi pond. I am thinking about using isomalt for the pond, though I've never worked with it before. Is there a way to make the koi fish visible through the isomalt? Will I need to just make a flat isomalt time for the pond, and put the fish underneath it? Any other ideas or suggestions?

You could cut the orange fondant fish and put tinted piping gel over them.

Maybe the customer needs to provide a goldfish bowl with real koi for the top of the cake...