If either or both said Strigata then I would take their word for it. They are both very knowledgable about cichlids and fish for that matter.
Pikes usually don't bother other types of fish that aren't pikes. (unless they can fit them in their mouth)
You can't go wrong if you try to add a Marmorata, In fact it is my favorite species of Crenicichla. ( See my avitar, it is my female marm)
Marms get very thick and robust also.
Like I stated earlier, I would make sure it is close if not bigger than your current Strigata resident. Definitely nothing smaller than 2" less than the
Strigata.
Add the new pike when you have some time to observe them for a while
cause things could turn ugly. But with a 600 the odds are much better.
GL and welcome to the world of Crenicichla. I can become addicting!
There is no doubt that this is a true strigata. I have two myself and they look indenticle to yours. Very cool pike and very rare. I have my two in with two lenticulata. They share a 900 gallon tank with very little aggression. I am hoping to add my 13" female marmorata in with them as well. Good luck
with 600 gallons, im sure you would be alright adding other pikes to the tank, I would think that adding more then one would be better then just one in your case being that you have a large, established pike in the tank.....Maybe another 2, possibly three and i've seen pics of the tank, huge, im betting that as long as they have there own 'homes' there would not be to much aggression, plus there are plenty of other fish in that tank to keep them occupied. But, you never know, pikes can be mean as hell and i've heard of some that did not allow tank mates at all, to others that can live with multiple pikes in not to large a confine.
with a tank that large, and additional 2 pikes I think would be fine as long as they are around the same size......There may be some fighting at first just to establish a hiearchy but it should calm down once that gets figured out and each pike takes their own territory.