If you want to give it a shot, use a divider.. I don't see a 10'' red devil letting a smaller female severum live long.
What size tank are you thinking of using?
maybe they are made by milking the fish... get a large severum-like fish, a large RD and tranquilize them... Then, pick em up, and squeeze the belly and massage it gently so the guts don't come out.
Thats how they breed salmon in hatcheries (I'm a certified atlantic salmon breeder lol)
I have lots of stories to tell about my adventures breeding salmon, but they aren't hybrids so I'll keep it short
I had 200 salmon eggs in a 20 gallon long tank with a chiller. They need specifically 36-38 degrees fahrenheit because they need the extra dissolved oxygen and they hatch in the winter so the temperature simulates their natural environment. They hatched into alevin. Then some of them turned into fry lol.
Then disaster struck.
I put a sponge over the hang on the back filter, and the sponge fell off and the fry were sucked in. Luckily, only 2 died from that ordeal.
Then, when they got to about 2 inches, I took all of them (about 180 left) to the Merrimack River in New Hampshire and dumped them in (Breeding salmon is a government funded job for the Marine Fisheries of New England so I was authorized to release the fry)
It was pretty fun watching the fry swim out into the river, where they will travel downstream into the dam's fry ladder (which is basically an outflow waterfall next to the dam. The current is stronger there so the fish know to go that way. The other side, theres a fish ladder and sturgeon and alewife and other fish migrate up that ladder)
We also went fishng (to bring down the bass population to protect the fry lol it doesn't really work but I get paid to do it)
Anyway... I just started telling a story after talking about milking fish.... weird...