WHERE Clause Does Not Work. Why?

I am asking for help to resolve this simple problem. It is a stored procedure. It is supposed to return a single row from a table. The table may have max 300 rows but now there is only one row in it. When I execute the query in SQLEXPRESS in the New Query Editor Window with the correct parameter it returns empty row.

set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE [dbo].[CentrCtrl_SelectStats]
@symbol varchar (10) = 0
AS
BEGIN
SET NOCOUNT ON;
SELECT * FROM dbo.CenC_stocksStats WHERE symbol = '@symbol'
END

Now, I varied this simple statement this way and that way. I changed it into

SELECT * FROM dbo.CenC_stocksStats WHERE symbol = @symbol

with the same negative result: empty rowset.
If I remove the WHERE clause, the resulting set is OK--it is what I expect, but now the table has a single row and I do not want to have the entire table when it gets bigger in my C# code if I could retreive only the row corresponding to symbol I need. What is my problem in here? I am at a loss.

Thank you.