I agree,
a 100 gal tank is way too small for even the smallest species of Cichla.
It's not just about their size, but the running room they need, they are a very active strong swimming clade.
The two above, (and their fry) were the only 2 fish in a 250 gal tank, and they made it appear tiny.
To me a 100 gal tank is too small for any cichlid that gets over 10", which excludes many pike cichlids.
So maybe a pair pike that get no larger than 10", or depending on your water parameters, something medium size from Central America
A central American that might work for that size tank, would be Nandopsis tetracanthus (left below) or Chiapaheros grammodes(right) (if you have harder high pH water.
Of course in that size tank, I doubt if either of those 2 species (or any substantial size predator) would allow any tank mates.