Salvini has been a commonly available cichlid for quite some time now. They were available from the box stores pretty much 365 days a year for almost a decade. But sometime about 2 years ago, the box stores stopped carrying them. I think a lot of people tried them and for what ever reasons, they did not really catch on. Tried briefly and then moved on to something else. Now, many of the pet shops stopped carrying them due to low demand.
It's the bright colors that initially draws many people to salvini. But I see 2, possibly 3 main reasons, why salvini has not really caught on.
1st is it's aggression. Particularly males and/or pairs can be very nasty. But IMO it's primarily dependent on what you keep it with and size of tank.
Secondly, in many situations, the fish can stay scared, become very skittish and hide. IMO it needs an active, well stocked tank to be comfortable in. The larger and older it gets, the more prone it is to becoming overly fearful.
And thirdly, I suspect that salvini is less tolerant of poor water conditions then most CA cichlids. It needs decent water conditions to thrive (unlike say, the convict cichlid which will do OK even despite poor water quality).
So first, I'd like to discuss tankmates. In the 18+ years I've been keeping the fish, I've kept salvini with quite a variety of fish and other cichlids. List of all the fish I have kept it with:
CA Cichlids: Convicts, Jack Dempsey, Dovii, Black Belt.
SA Cichlids: Oscar, Red Terror (Mesoheros festae), Angelfish
African Cichlid: Coptodon zillii, Jewel cichlid (Hemichromis guttatus), Zebra Obliquidens (Astatotilapia latifasciata), Astatotilapia bloyeti
African cichlid from lake Malawi: "zebra" types of some sort, Auratus, Kenyi, Bumble Bee (Pseudotropheus crabro), electric yellow, Demasoni, Acei, Sunshine Peacock, Electric Blue ahli (Sciaenochromis fryeri.
Non cichlids: Red Bellied Piranha, Red tailed shark, Rainbow shark, blue/gold/opaline/3-spot gourami, Moonlight Gourami, Giant Danio, Common Pleco (Ptergoplichthys pardalis, BN pleco, Chinese algae eater.
I have kept Salvini in 6 ft. tanks, 180 gal and 125 gal., and in 4ft. 100 gal., 90 gal. , 75 gal. (usually at younger and smaller size), and as very young fish in 33 gal, 29 gal. and 15 gal.
At least in the size of tanks I have, many on this list have proven to be far too violent, and would never house them together again. IME, salvini get along well enough with all the African mouth brooders I have kept them with. Sturdy bottom feeders and loaches usually do OK, and gouramis usually receive even less attention. IME, always a lot of "friction" with male salvini and any other substrate spawning cichlid, though single females have gotten along considerably better.