How large is the tank? That is more of a risk having a Cuban with a Dovii, even if the Cuban is at the same agression level of a midas, where I have seen a male midas take on a dovii and the midas still lost badly. The owner had a 600 gallon tank as well.
I have kept them in the past. Pretty typical Central American attitude on these fish. My Nandopsis tetracanthus coexisted with a mixed group of Herichthys tamasopoensis and H.bartoni without too much of an issue for several years. They were more concerned with attacking and killing each other than going after other fish.
I would rate them as being fairly aggressive fish overall.
My male at 5" ruled over a 6.5" Freddy.
The Cuban didn't start anything, but would not back down& usually chased The Freddy away.
This was in a 120gal (4/2/2)
With 6 Freddies total, a female Cuban& 5" L-191
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