conductivity

Hi everyone. I am going to enter BADC 2022 and I need scientific explanation for this following questions: 1. What is conductivity? Is it the same as TDS? 2. Does low conductivity related to low pH? 3. Is poor mineral content the same as low conductivity? Cheers Barry

What are ec levels what does it affect and what are dangerous levels even if it is dangerous to fish, I know it's to so with the amount of positive ions in your water but how does it affect fish and what is ec in detail?