What is the minimum balance for E-Trade?

Excuse me, could you please clarify for me the specific requirements regarding the minimum balance for an E-Trade account? I'm considering opening an account with them but I'm unsure of the minimum funds required to maintain it. Is there a standard minimum balance that applies to all E-Trade accounts, or does it vary depending on the type of account I choose to open? Additionally, are there any penalties or fees associated with falling below this minimum balance? Your insights would be greatly appreciated.