The Volitans and Russels is not an open water fish, they are fish that will venture out into open water to hunt. They perch like the rest. Other lions couldn't be bothered to hunt out in open water and tend to stick closer to the bottom and the rocks to hunt. That really doesn't make a difference though, as none of our tanks offer "open water" to a lion. In our tanks they are very close to the bottom of the tank and very close to rocks, that's not open water by their definition. They don't hover, they swim, so our tanks offer very little in the way of encouraging that natural behaviour. Because they can't really swim, they perch just like the rest. All lions tend to get a little lazy when they are adults, but this is even more so with the larger species. You Russels will ultimately spend more time on the rock and take up more room on the rock than an Antennata. Does that make sense at all? I can try to explain that a little differently, as I feel I muddled that one a little.
Antennatas are prettier.
They are both the same as far as personality.
Both the same as far as converting to frozen.
My Russels could have eaten my fuzzy.