Pimelodus pictus is the scientific name that is going to get big.
Let me say this since I used to sell them, they are cute when they are small and swim around a lot, but when they get older they lounge and don't do as much. People lose interest in them quickly when they hear that.
You have the right idea about asking for advice before making the purchase, I applaud that.
This is one decision I would want to stay away from just b/c of the end results that will come of the purchase of these fish.
I hope that this helps.