The lateral Line is used to detect currents emitted from the surrounding enviroment. Fish give off electrical fields just like we do, and they can detect this with the lateral line. Tank electrical equipment can develop a "leak" which will overload the lateral lines of fish over time and lead to the degenerative condition we call lateral line disease. I would buy a probe which is really easy to install to eleviate this. These probes cost around 20 bucks, and can be installed in about 2 minutes.
A varied diet is also essential for health over the long term. Don't lock onto one food. I rotate between 4 or 5 different types of frozen and flake. Some diehards even make their own.