Rbp are very skittish and using don't meet most folks expectations. Maybe in such a school that isn't the case. Caribe are gernerally more favored but more expensive.
Arowana, gars and rays all day long, go black Arowana tho as silvers always get drop eye. Add a big shoal of spanner barbs and a tyre track eel. Do some googling.
Also silver are get over 100cm not 75cm!-)
Your options to add fish will be much wider, if you were to go piranhas it's only piranhas forever or sell up.
As above caribe red belly are the way to go. Or piraya if you can get them that would be special.