Well there are many postings and stickies regarding the different species of datnoids so you should probably check them out and decide which ones you would want to buy. The silver dat (AT) are the cheapest and IMO the easiest to keep. NTT's are the second level up on pricing and a little easier to find at LFS. NGT's, IT's and ST's are much more expensive and harder to find.
One thing that you should know about dats is that you need lots of patience in regards to stability (dark stripes with gold body) and feeding. In general dats are very finicky about what they want to eat, and could cause you grief in regards to what you want to feed it. Many members here have successfully gotten their dats on pellets, MP, or talapia, and reading their posts on how they converted them is very helpful.
Another major issue with dats is that they can be extremely shy (hide all the time). Some members prefer bare tanks over tanks with hiding spots but thats really up to how you want to set up your tank. Usually when you first introduce you dat to the tank its not gonna be swimming around alot and feeding from your hand. It usually takes time (alot or a little) for them to get used to their tank and you.
In regards to keeping them with your pbass, just know that dats take a lot of time to grow, especially from 6" and beyond. I bought many 1-3" NTT's and in a period of ~1yr they have only grown 2-3" in length. However, it is also important to realize that you will see them grow in height and girth (kinda like a football). This is also the reason that big dats cost alot.
Anyways good luck on whatever dat you pick out and post some pics!
