The first thing we need to know is water parameters. What is the GH and PH of your school’s water source?
That stocking sounds rather problematic. Kuhli loaches need groups of 5 or more, minimum, with 8 or more being ideal. Same for the Congo tetras. I would stay away from sharks altogether. That also sounds like a whole lot of cichlids for one tank! If you are set on this stocking, (depending on the water parameter) I would encourage you to have a group of 12 or so kuhli loaches, 12 or so Congo tetras, a pair of Angel fish, and drop the rest. I am not too familiar with angelfish, but a pair would likely be your best option. If that’s incorrect someone please correct me and I will edit my post!
If it were me, I would go for something medium sized and colorful. Easy to see and striking. Something has personality and isn’t shy, but also won’t cause issues or overstock the tank. With it being in your school, you won’t have constant access to it. I would suggest Electric Blue Acaras. They get to be about 5 inches, are bright blue, have loads of personality. It would fit the tank size really well too. I think you can do all male groups. You could likely do something like a school of Cories or a cool pleco for the bottom. This was my male. He definitely didn’t get along with the tetras, but the bottom dwelling fish were just fine.
I think that EBAs are obscure enough that “common people” will think “wow look at that unique fish”, but hardy and popular enough that you as a fish keeper wouldn’t have many issues finding and caring for them.
Edit: I also want to add that a thriving, healthy tank with thriving, healthy fish is more appealing than a tank full of colorful fish that aren’t doing well.
