most people here have not kept adult cichla. if they did, they would know better than to say 100g is good enough

until you see in person how big these guys can get, you dont know. until you see the speed and power of a 18" orino or 22"+ temensis when they go all out, you dont know. i had mine a 210g for a few months. even when they were just a few inches, the tank seemed too small. then i moved them to the 400g. after a while it just didnt seem big enough. keeping them in a 125g seems downright cruel to me.
the truth, whether you like it or not is, people buy cichla because it's the "cool" fish to have. the truth is, a vast majority of people cannot care for them properly. myself included, that's why i got rid of them. everybody likes to buy little guys and grow them out. but they dont know what theyre in for. cichla are not easy to keep long term. they get huge, are messy, can move like lightning and the bigger they get the more sensitive they are to water parameters. HITH is a common problem with big cichla.
in my opinion 400g is too small. 300g is too small. 100g is just plain cruel. if i were ever to do it again, and i planned on keeping them for life, not to just to grow them out for a few months, i wouldnt not get them unless i could fit/afford a 750g tank or bigger.
if you can afford a big tank, dont buy big fish, it's simple. unless you dont care for the fish and just to do it to fit and and show off. there are plenty of cool ca/sa cichlids that would go great in a 100g tank. bottom line, cichla is not one of those fish.