hey all, i got a new 120 up and running, only a few peacocks in their now but soon to be filled with malawi and tanganyika cichlids, how do i sex them? and if they breed i'm guessing other fish in the tank will eat the fry?
raising fry in a mixed tank is a lost cause, yes... unless the male of the brood decides to kill everything in the tank, then the fry are quite safe
But in a 120 you shouldn't have to worry about the latter.
Malawi mbuna males can be somewhat-reliably sexed by the presence of eggspots on the anal fin, *shown in the pic at the bottom of this post*. mbuna females (generally) lack these eggspots
sexing malawi haps and tanganyikans is another matter entirely, and sexing varies from specie to specie.
here is a very good profile listing of common african cichlid species, that I suggest you use to identify and sex your fish, when you get them: http://www.cichlid-forum.com/articles/species_profiles.php
Finally, I'd suggest that you AVOID mixing malawi mbuna with other african species. The reasoning behind this is that despite the fact that they are often smaller, mbuna are generally still much rougher and more aggressive than other african species-- you might find it very depressing to see the mbuna residing in bliss in all the decorations and caves within your tank, while the tangs and haps are all constantly cowering at the top of the tank in fear.