I'm assuming you mean your local public library ... And not a library room / study at your home. If so, mention to them that the two TB's will probably eventually bully the other fish as they mature (assuming they're juveniles).
Adding another 4-5 will go a long way to shifting their aggression on each other.
Also ...mention to Turn up the heater in the tank to 88F if there is Ich. I'm wagering If the tank was filthy a few weeks ago, I'd give them another few weeks ... Maybe months before you see the same. Your indicator will be if they treat the possible Ich issue.
75g Planted Barbs Denison, BlackRuby, Tiger, Albino Tiger, Green Tiger, Cherry, Gold, Checkered, Odessa.
NonBarbs Cardinal, Neon, RummyNose, Bloodfin Tetras, Z. Danios. 1RTS. Amano, Bamboo, Ghost & RCS. 20g Long Shrimp Tank RCS, Tiger, Amano.