possible shark tankmates for
RTBS include other semi aggressive fish like the numerous barbs and danio species. Also, you could include species of large tetra like bleeding hearts and black widows. For bottom dwelling movement, corydorases are everyones favorite.
You should only include one RTBS in your aquarium as they like to fight and become far too aggressive with each other as they age. They will also quarrel with similar looking fish like the rainbow sharks, albino variations of both rainbows and red tails, as well as the siamese algae eaters and flying foxes. Only one red tail shark should be added to an aquarium.
Also, i read your aquarium information and it looks like you don't know about the
nitrogen cycle. All aquariums must go through this before adding fish. Read up on this article for more information:
http://www.fishlore.com/NitrogenCycle.htm