10gal for a,
'A', SA/CA cichlid, as in one adult male display fish, perhaps with 3-6 small tetras for dithers...
There are a couple of choices possible, but just because something is possible doesn't mean we should do it.
Almost all of the Dwarfs/Apistogrammas are very sensitive to water quality.
A 10 gal is very minimal, and minimal means less room for error and increased maintenance intervals. Water volume is your friend, as is moderate stocking levels with heavy filtration.
Most of the Dwarf/Apisto prefer a small harem/breeding group, one male and 3+ females, with room for each female to have a small territory.
I strongly suggest you acquire a 20-30gal for even Dwarf/Apisto, then you can do a nice little slice of SA/CA with the best interest of the fish addressed.
That said, your gonna do what your gonna do, so I'll attemp to continue to point you in the right direction...
http://fish.mongabay.com/apistogramma.htm
You could technically keep any of these as a solitary male with the formentioned school of dithers in a 10gal...
But I wouldn't recommend it.
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You cannot raise and keep a Sev in a 10gal.
To do so would be cruel, inhumane and negligent.