Read a file from a FileStream and get the bytes. Pass the bytes to a new method and try to read it there with the right encoding.

gistfile1.txt

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace StreamReadWrite
{
    class Program
    {
        static void Main(string[] args)
        {
            string pathSource = @"c:\trash\foo.txt";

            using (FileStream fsSource = new FileStream(pathSource,
                        FileMode.Open, FileAccess.Read))
            {
                // Read the source file into a byte array. 
                byte[] bytes = new byte[fsSource.Length];
                int numBytesToRead = (int)fsSource.Length;
                int numBytesRead = 0;
                while (numBytesToRead > 0)
                {
                    // Read may return anything from 0 to numBytesToRead. 
                    int n = fsSource.Read(bytes, numBytesRead, numBytesToRead);

                    // Break when the end of the file is reached. 
                    if (n == 0)
                        break;

                    numBytesRead += n;
                    numBytesToRead -= n;
                }
                numBytesToRead = bytes.Length;

                WriteConsole(bytes);
                WriteConsoleBetter(bytes);

                //string content = Encoding.UTF8.GetString(bytes);
                //Console.WriteLine(content);
            }

            
            using (StreamReader reader = new StreamReader("c:\\trash\\foo.txt"))
            {
                int readBytes = 0;
                int increment = 100;
                char[] arrayToFill = new char[reader.BaseStream.Length];

                while (reader.BaseStream.Length >= readBytes)
                {
                    int currentReadCount;
                    if ((readBytes + increment) > reader.BaseStream.Length)
                    {
                        currentReadCount = (int)(reader.BaseStream.Length - readBytes);
                    }
                    else
                    {
                        currentReadCount = increment;
                    }

                    reader.Read(arrayToFill, readBytes, currentReadCount);
                    readBytes += increment;
                }

                //var content = reader.ReadToEnd();

                string content = new string(arrayToFill);
                Console.WriteLine(content);
            }

            Console.ReadLine();
        }

        private static void WriteConsole(byte[] bytes)
        {
            using (MemoryStream stream = new MemoryStream(bytes))
            using (StreamReader reader = new StreamReader(stream))
            {
                int readBytes = 0;
                int increment = 100;
                char[] arrayToFill = new char[reader.BaseStream.Length];

                while (reader.BaseStream.Length >= readBytes)
                {
                    int currentReadCount;
                    if ((readBytes + increment) > reader.BaseStream.Length)
                    {
                        currentReadCount = (int)(reader.BaseStream.Length - readBytes);
                    }
                    else
                    {
                        currentReadCount = increment;
                    }

                    reader.Read(arrayToFill, readBytes, currentReadCount);
                    readBytes += increment;
                }

                //var content = reader.ReadToEnd();

                string content = new string(arrayToFill);
                Console.WriteLine(content);
            }
        }

        private static void WriteConsoleBetter(byte[] bytes)
        {
            using (MemoryStream stream = new MemoryStream(bytes))
            using (StreamReader reader = new StreamReader(stream))
            {
                // This is enough the change the encoding of the StreamReader in a right way.
                reader.Read(new char[1], 0, 1);
            }
        }
    }
}