FormateException Was UnHandled

Why don't you create an Employee class so you don't need so many synchronized arrays:

class Employee
{
   public int Code {get; set;}
   public string Name {get; set;} 
   public int Age {get; set;}
   public string Address {get; set;} 
   public string BloodGroup {get; set; } // needs to be a string as char can't accomodate 'AB' blood group
   public int Salary {get; set;}
}

public class BloodGroupDetails
{
   public Employee[] Employees {get; set};

   public void GetData()
   {
      Console.WriteLine("\n How many employee details are going to be entered:");
      int n = int.Parse(Console.ReadLine());
      Employees = new Employee[n];

      for (int i = 0; i < n; i++)
      {
         Console.WriteLine("\nData for employee number {0}", i+1);
         Employees[i] = new Employee();
         Console.WriteLine("\nEnter the employee code:");
         Employees[i].Code  = int.Parse(Console.ReadLine());
         Console.WriteLine("\n Enter the employee name:");
         Employees[i].Name = Console.ReadLine();
         Console.WriteLine("\n Enter the age:");
         Employees[i].Age = int.Parse(Console.ReadLine());
         Console.WriteLine("\n Enter the address:");
         Employees[i].Address = Console.ReadLine();
         Console.WriteLine("\n Enter the blood group:");
         Employees[i].BloodGroup = Console.ReadLine();
         Console.WriteLine("\n Enter the salary:");
         Employees[i].Salary = int.Parse(Console.ReadLine());         
      }
   }
}