Please note this info is only my opinion...
Your tank volume is approximately 566 Litres, 126 Imp. Gals, 149 U.S. Gals.
Theoretically, you can accommodate 27 Tropheus of 3.5 inch (8.9 cm) in this tank.
As Adults:
This tank can accommodate a total of 32 adult Tropheus, if there are 1 species. The tank is an okay choice (longer would be better), adults should do alright in this tank.