The side movement of fish is an indication of the feed of fish from planton. It makes side lateral moves and target its pray which is invisible to the human eye. Fish when they receive ultraviolet light they may repsond opposite according to which species and camouflage themselves by emmiting infrared light and this is an assumption because the humans do not know everything about the sea.
Robot that has a sensor to see different scattering patterns of light according to which chemical element. Function to pick up similar chemistry, function to deposit on piles the similarities. The easiness to that is that the robot can make it to distinguish far elements in the period table such as lead from carbon.
The application of electricity to the water will take oxygen out of the tank and it will produce sulfur, and feron, but steel will receive the hits from the chain of reaction, which include helium and microparticles such as protons. The result would have more minimum chances to be feron oxide because oxygen are missing. The chances would be to give a harder metal.
By putting graphite in the water this may mean that an easy neutron can cause a nucler type of a cleaning process.