In Connecticut, when a levy is issued can the creditor take all monies available in your personal bank account or must they leave a minimum amount for essentials such as rent, utility bills, etc.

All the money up to the amount of the court order.

There is no one "min" someone may have rent of 10,000 a month, another 400 a month.

To get a levy ( garnishment) there has to have been months of bills, you were served with notice of a court hearing for a judgement.
After that you should have known they would be coming after the bank account??