TANK REQUIREMENTS
While the water parameters for keeping the P. loisellei is easy to achieve, I believe the biggest challenge in successfully caring for them at home is the tank size. While they are generally a medium to large Cichlid, they are quite aggressive and territorial. Hence, putting them in a big tank is a must.
I would recommend a tank size of at least 75 gallons if you will have 2 to 4 specimens. While it is no guarantee that you will be unsuccessful in a smaller tank, you will surely be faced with a lot more challenges in a relatively smaller tank than a bigger one, especially when they grow up. You will have even bigger problems when they mature.
If they do breed, you will have front row seats to experiencing the wrath of Cichlid parents protecting their brood from the tankmates, who would all try to fit themselves to the 1/5 section of the tank that is farthest from the nest.
To avoid such troubles, put the P. loisellei in the biggest tanks you can allot for them. Otherwise, you will just lose them one by one in a small tank, since they will eliminate the weaker ones until they are able to coexist amongst those left over.
Just because the P. loisellei is aggressive, this does not mean they cannot coexist in a community aquarium setup. A huge tank is a must if you will have a community of aggressive Fishes. There are many choices available. Forget the good guys; your tank will have to be a tough neighborhood. We are only considering Fishes who grow more than six inches, are aggressive, hardy, and fast.