A colony of Sajica (T-bar cichlids) would look awesome in that tank! 180 is a good size and you could do a community of larger cichlids, but it usually takes a good amount of tweaking to get the mix of species right. Doing a colony of one species of smaller fish like the Sajica will make it more beginner-friendly for sure. I would recommend around 15 sajica for that tank size. You could keep a large school of swordtails in there as well, that would keep the tank central-American themed and would provide a large supply of babies which will be eaten or could be periodically traded to a fish store for credit/food.
Atabapo pikes are awesome and you could do a small group of them in there. As you stated they are expensive however.
What is your tap water like? pH, hardness? That will make a difference, as it would be wise to pick fish that thrive in your water. Sajica and pikes like opposite ends of the pH and hardness scale (although most cichlids are adaptable anyway)[/QUO
I'm in a new apartment and haven't checked the water yet. 15 sajicas sounds like alot, no ? I was thinking 7 or 9. I love the idea of swordtails. How many for a school do you suggest ? I'm thinking 20, no ?