Each exchange has its own minimum order setting. What I've learned working with CAT is that profits from very small orders dont really worth your time - unless they are thousands of them.

And yes, Bittrex is an excellent exchange but the fees they charge are too high :-(

Edit: small orders get fulfilled faster but it is pointless if you just get a few satoshi each time. The key is simple: give CAT coins and let it do its job. Even if it seems stuck at a higher or lower price, don't chicken and call it off. Instead, let the order for 2-3 hours at least to see if it gets fulfilled, stop ping creation and seek another market as a backup.
Always study the market pair you are thinking to trade, never start CAT blindly. If you are unsure, do a couple of trades by hand first to see how the market moves.