Yes it is your thread.
As far as getting a pleco, DON'T. They need much much more space than you have. I have a 10 gallon and I find it too small for a lot of things. There is a very limited amount of stock you can add. I would stick to small tetras like neons and flames. You could put a couple of the smallest type of gourami- croaking/sparkling. Your corydora are going to get awfully big for that small space and they don't do well unless they are in larger groups... So I wouldn't even suggest them.
The smaller the tank the harder it is to find a good community of fish that will live happy and healthy.
(I am referring to the 5.5 gal)