Thanks!
In the thread I do post some pictures of my German Rams and their fry so you can see there the differences. German Rams are somewhat smaller and certainly very vividly coloured. Bolivians do have a lot of colouration to them, but it is very subtle and that's a lot of what attracted me to keeping them.
Anyway side by side comparison...
Bolivian Ram:
German Ram:
Bolivian Rams work well in groups as they are a very social fish, but they can also be kept simply as pairs and if the male is not too aggressive, in a 1m/2f group. I would recommend a minimum of 30 gallons for a pair or trio, the space is good for them. They can tolerate a pH of between 5 and 7.8, but I wouldn't recommend keeping them in a pH of lower than 6 or above 7.6. Temperature ranges of 26-28C.
German Rams work better IME as pairs to their own tank, a 15-20 gallon tank is usually quite suitable for a pair, I've also successfully bred them in a 10 gallon tank but removed the fry once free-swimming. When keeping German Rams I tend to have the tank dedicated to them with the occasional hardy dither. The reason for this is that German Rams are much more prolific at temperatures of 28-32C and most fish are unable to tolerate this temperature. German Rams can live at lower temperatures, I have even bred them at temperatures closer to 27C, but their colouration, developmental rates and general activity seem to fare better in warmer conditions. pH of 4.5-6.
Another thing to mention is the water softness, German Rams really need very soft water - KH of 2 is what I kept them at, pH of 5, 30C, their fry will not develop in harder water and generally they aren't as colourful IME.
Bolivian Rams however are somewhat more hardy and tolerate a wider general range than German Rams, I've kept them in KH2 pH5 to KH4 pH7.5 and had great success throughout the range with both health and breeding. Generally though I opt for a KH of 4 and a pH of 6. Others have kept them in harder water, but I couldn't comment on that.
Bolivians tend to their young better than German Rams who frequently eat their fry, many theorise that this is due to excessive stripping of fry causing them to lose their parental instinct, I couldn't comment on that either, but they don't seem to be the best parents in the world (in aquaria) and that's a fact.
I much prefer Bolivians because of their appearance, attitude, curiosity, intelligence and character, they really are cool little fish that always want to know what you're upto. They are truly comical and also very brave. I have video's of my Bolivians standing up to and chasing off my 7" Rotkeil severum! German Rams are very pretty, but just don't seem quite as bright, lol.
Sexing guide:
Take into account the only real way of knowing is venting them or seeing them spawn, the other details I will show you are just generalisations of what you would expect in differences between the sexes....
First up, ventrical differences:
Click to enlarge!
Notice how the males vent tapers back and is considerably smaller whereas the females points more downwards and is visibly fatter.
You can also see the difference in the length and shape of the pelvic fins, although this is not a sure-fire way of telling it can be an indicator.
Picture A. is of a female, I'm pointing this out first as you can see here that the females dorsal looks similar to what one would expect from a male:

You can clearly see her extended ray on the dorsal fin. So I'm not saying this is a way to sex them. You can see for yourself that females too can express these predominantly male characteristics.
Picture B. is also of a female:

Here too you can see the extended pelvic fins that you could expect on a male....
Point made?
Now onto the comparisons (generalisations, whatever you want to call it.)
With that said, picture C. is of a male - you can clearly see the extended 3rd and 4th rays on his dorsal fin:
Picture D. shows a "typical" female dorsal fin, you can see the progressive slope that I with no particular spine elongated.
Picture E. shows a "typical" female head shot. You can see it is more rounded when compared to Picture F.
Picture F. is the male head shot:
Pic G. showing the extended rays on the Males tail fin:
Pic H. shows the "typical" female tail and as you can see, even they can possess slightly extended rays:
Like I said other than venting there is no guaranteed way of knowing, however the differences you can see above (however slight) can help.
I've got videos of them spawning and being super aggro, loads of photo's etc, if you want to see anything just ask!
HTH!
Blair.
My "sexing guide" may be posted elsewhere as long as I am credited, I made it to help people out, so I hope it can be of use....