Okay, bear in mind that rainbows are slow growers, so any you get are going to be around 2-2.5" to start and will usually look blah. Many don't color up until they are closer to 4-6 months old. All of the sizes listed are approximate. All of these fish can, and probably will, exceed the sizes listed, although it will take some years for them to do so.
I have only listed bows that I know are available in the US in aquaria, that are fairly deep bodied or VERY deep bodied. Some are very rare and you won't find them in your LFS. I have probably missed a few, too.
Melanotaenia Species
Melanotaenia boesemani, Boeseman's Rainbowfish, 3½-4", blue, yellow/orange/red
***
Melanotaenia trifasciata, Banded or Regal Rainbowfish, 4½, Color depends on origin
Melanotaenia duboulayi, Crimson-Spotted, ~4", multi colored
***
Melanotaenia affinis, New Guinea Blue, ~4½", Blue, whitish undersides
Melanotaenia maccullochi, Black Lined Rainbowfish, ~3"
Melanotaenia parkinsoni, Parkinson's Rainbow, ~4¼", popular fish, but does not get very deep bodied compared to others
Melanotaenia parva, Lake Kurumoi or Flame Rainbowfish, ~3", extremely rare, red and gorgeous
***
Melanotaenia herbertaxelrodi, Lake Tebera, ~4", Yellow with black bands
Glossolepis Species
Glossolepis pseudoincisus, Millenium Rainbowfish, ~3", very red, very rare
***
Glossolepis wanamensis, Lake Wanam, ~4", Green
Other Specie
Chilatherina bleheri, Blehers Rainbowfish, ~4"
Chilatherina fasciata, Barred Rainbowfish, ~4"
Here is a link to an article written by Christophe Maillet on parva and pseudoincisus:
http://members.cox.net/roanart/Tanks/'Those%20little%20red%20fish'.pdf that has some awesome pictures of these rare fish.
Anything with
*** is a bow I have in my tanks.
My top choice would be the Boeseman because I know they don't put up with any crap from other fish
They also grow to a decent size and are not too pricey.
Hope this helps,
Roan
