Microgeophagus ramirezi, the Ram

Microgeophagus ("Papiliochromis") ramirezi (Ram). The particular Ramirez immortalized in our "Rams" is Manuel Vicente Ramirez; he and Hermann Blass from Florida collected the fish in 1947 in the llanos grasslands of Venezuela, on the left bank of the Orinoco. Blass imported some specimens and bred them, calling them "ramirezi," a name confirmed when they were scientifically described by G.S. Myers the following year, as Apistogramma ramirezi. In 1978 Sven Kullander confirmed aquarists' perception that the morphology and behavior of these fish stood them apart from Apistogramma species, naming them Papiliochromis;  he ignored an article by Herbert Axelrod in Breeding Aquarium Fishes, vol. 2 (1971) that used the name Microgeophagus introduced by Hans Frey, who had informally discussed the divergence of these species in 1957 and in hobby-oriented books afterwards, so that it's sometimes been a moot point which name has precedence; some even advocate the spelling "Mikrogeophagus".
 
Very sporadically, wild-caught fishes from the south of Colombia used to be available, but I surmise that political turmoil in that contested region has eliminated that possibility. All the Rams you see in the US market are tank-raised in southeast Asia. In Europe fishkeepers are glad to pay a bit extra for  "German" or "Czech" Rams.
 
Generations of tank-bred Rams have lost the intensity of iridescent blue sheen on the flanks, dazzling in reflected sunlight, in wild fish. "Electric Blue" rams appeared on the market in 2009. Amelanistic mutations have produced "Golden" Rams, in which the normal admixture of melanin is suppressed, revealing the yellows that are usually olives and the pinks that are normally grays; in these, you'll miss the iridescent blue sheen altogether.  A poor development of captive breeding has been the shorter body length, which you should avoid as a flaw. And there are long-finned versions that might appeal to people who'd really prefer goldfish.
 
In spite of its origins in the open llanos grasslands of the Orinoco Basin, aquarium lore has built up a picture of Rams as rainforest fishes. The continual inbreeding for more intense color, which has resulted in a miraculously beautiful domesticated fish far removed from its wild origin, has taken a sad toll on its delicate constitution. Modern manufactured Rams seem to be smaller, too, than the fish I remember from years ago. When you set out to buy Rams you ought to be looking for sub-adult fishes if you hope to end up with a pair. "Virtually all the fully adult rams now marketed in North America are males," Paul Loiselle noted in the July 1994 issue of Aquarium Fish. "This state of affairs suggests that the breeders in the Far East are either shipping only males, or more likely, they are artificially creating unisexual broods by feeding the young food laced with methyl testosterone at some point in their development." This same disheartening strategy lies behind the sterilized all-male populations of "Sunset" Gouramis.
 
Take it for granted that the Rams you've just bought are harboring bacterial infections and possibly intestinal nematodes. Praziquantel treatment for internal parasites should be a standard part of your quarantine procedure anyway. If you're attending a local club fish auction, young tank-raised Rams are something to be on the lookout for. From the same source, in your pursuit of a better chance at pair compatibility, a strategy is to buy a group of uncolored juveniles, less than an inch long. You aren't going to be able to distinguish a male's longer extensions of the first few dorsal spines, not in the young fishes you're buying, but you might look for the faintest hint of a healthy mature female's rosy magenta patch in her ventral region, and compare it to the male's more golden ventral area.
 
Joel, MN, reported experiments in 1998 with pH and Ram hatching rates, which were high at pH 5.5-6.0 but decreased to almost nil at pH 7.0, due to fungus. Fungus of eggs is often counteracted with methylene blue, but Joel's experience suggests that peat filtration might help raise the proportion of viable eggs. Rams want warmth, about 80°, and for encouraging breeding, you can push the temperatures to 86 to 90 degrees. These steamy conditions will eliminate most gill parasites too. With extremely soft water and peat filtration producing tannin-laden acidic water, fungal spores and bacteria tend to be suppressed too. In these conditions, Rams will start to thrive, not just get by. At low pH, nitrifying bacteria are slowed or suppressed; you'll need dense healthy plant growth to scavenge ammonium.
 
Mike Edwardes  intentionally bred a Singapore male (they're all males) to a German female to get closer to a wild-type Ram, but his final conclusion was that many complaints about Rams' delicacy are due to environmental issues like water, temperature and age of the breeders, rather than genetics.
 
Links. Mikrogeophagus ramirezi at FishBase.There are lots of posts concerning Rams archived at The Krib. Don Zilliox begins by letting a group of juveniles grow up together and form their own pairs. He's got some solid and very specific advice about breeding Rams. Greg Ure offers a brief overview of the species at the  Queensland Cichlid Group site.