Takashi Amano is on the floor of his living room, demonstrating the best way to appreciate his nearly 2,400-gallon fish tank.

"Lie on your back and look," urges the 58-year-old photographer and designer, gazing up at the aquarium's 13-foot spread, which is pierced by tree branches from the Amazon that crawl with plant life and swarm with schools of silvery fish. "You feel like you're inside," he says.

Mr....