"Floating Fish Dome" sold by German gardening equipment maker "Velda" is a product for floating carp in a pond.
It is a hemispherical dome, and when you fill it with water and float it on the surface of the water, the carp will come up and you can enjoy various appearances.
The dome also acts as a convex lens, so the carp can be magnified and the health condition can be observed. It seems that the carp will recognize it as a passage if you put the food together at the beginning of use.
It seems to be fun even in parks and rivers, but it may be a little scary if you pass by at night and meet your eyes.
The approximate size is 71 x 28 cm in diameter and weighs 4.7 kg. It costs $ 199 and is available on Amazon and elsewhere. Delivery to Japan requires confirmation depending on the store.
* All images are sourced from the "Velda" website.