Internet-enabled fish

In the linked idea, the ineffable [Ian Tindale] suggested making bacteria IP addressable.

With bacteria, this might be difficult. Howevertheless, it might work with certain fish.

Many species of fish use electric pulses to sense their environment. It is basically a low-power version of the electric eel's high-voltage pulse, but these pulses are much more frequent, and use very low voltages. By sensing how the field is distorted, the fish can sense their environment. They also sense the fields given off by other members of their own species.

The low-voltage pulses produced by these fish are modulated in frequency depending on their immediate needs (much like a bat's ultrasonic chirps vary depending on whether it is navigating or pursuing a moth).

So, here's the plan. We need a few of these electrosensing fish in a tank, a simple voltage detector, and a food- releasing mechanism.

Initially, the food-releaser is set up to release food whenever it senses frequent pulses. Gradually, however, the parameters are changed such that it releases food only in response to certain patterns of pulses. The feeder gradually becomes more and more selective, until it responds only to valid IP6 (or whatever it is) communications protocols. Gadulka! You now have internet-enabled fish.

Clearly, this could be taken further, depending on the fish's intellectual ability.