If you want a really special gadget for a fish lover, but not a gourmand, a person who loves alive fishes, in a tank, you can take a look at this Silverfish Aquarium, by Octopus Studios, which has six orbs connected by tubes, and this is a pretty cool design. The producer says it's not very difficult to clean it, but I think all aquarium lovers know what cleaning six circular aquariums means, plus the tubes.