From research ,I am learning and post , sometimes to be corrected, or validated.
Frontosa grow very large which means that, although they are not very active swimmers, they are going to need a big tank to house them!
4 fronts,(yes i know she asked about 2 /pair but they do better in gorups) so say in theory, 150cm (5 feet) long tank with a minimum volume of 500 liters ( about 125 gal. if Im correct) with 750 liters beeing even better!..
SO yes too small
awesome fish though