LionFish says.......
They sure are. I have never had a Fum Manchu but have had a few Radiattas in my days. They are pretty cool but I prefer Antennatas. But, yeah it would work. I would suggest that you have around 75 but no lower than 75 gallons. Get them at the same size, to keep their growing rate att about the same timelength. But the Fum Manchu doesn't grow to be as big as the Radiatta. The Fu only gets about 6 or 7 inches while the Radiatta can usually make a good 8 or 9 inches in a couple years or a little more. Just be sure to have a large enough tank to accomadate 2 lions. Hope this helps.