Altolamprologus Male 13cm/5inches females 9cm/3.5 inches... Males have a more massive head, as well as deeper dorsal and anal fins... They are a micropredator so they prefer small meaty food such as Brine shrimp, blood worms, and feeder guppies...
Here are a couple pics to help you with some of the different species... (Compressiceps & Calvus)
1)Black Calvus
2)Gold Face Compressicep
3)Red Fin Compressicep
4)White Calvus
5)Yellow Compressicep
would it be possible to keep one calvus and one compriceps together in a 12gal. if one was a male and the other was a female? if so, is there any possible that they mite breed?
12 gal is too small for thoughs guys you could do a breeding pair of shell dwellers
His guy is a Lamprologus Meleagris probably the coolest ones in my opinion they only get about 2.5 inches so they probably will work out okay in a 12 gal