Great idea 8

The great thing about the robo-fish is that they - once placed in water - losschwimmen like real fish. Looks really nice. By means of integrated weights can let the fish swim even more below or above.
Had more of them in the summer in the pool in use. The kids loved it and somehow it was fun to watch.
Batteries are naturally a bit expensive in the long run.
Outside of a pool, it is rather difficult to do with the fish bit. Small rounds in a bowl are not very impressive, also the whole room is playing wet.
Tried it with a small, square Kunsstoff Aquarium with lid. Here, however, the fish remained at the corners hanging and needed a lot of time and battery until it had since fought out again.
Thus might be well more than a round aquarium. Too small but it should not be there, the fish look good if they meet have room to swim.

This one here did not show after the first short test dive no function. Even after battery replacement. The other two fish my daughter worked, however properly.

I think there is a danger that children quickly lose their interest this toy. Because it is clear at first glance great zuzuschaun them while swimming - but that's it for now all they can and so one has seen quickly tired.