if you go to my profile i have some pictures of my gobies from when i had them, and with a 30, i would only do one. they are really rough on one another. by themself though they are still quite an attractive species, bouncing around from perch to perch and all. mine never bothered with the other fish so i dont think you'll have any problem with them.
the problem with the A. comp 'sumbu shell' that i suggested is that they are VERY hard to obtain. and if you can get your hands on some, be prepared to pay big, ive seen trios go for no less than $100. ive yet to find a place that carries them for cheap. if you do get some though i call first dibs on fry lol.
paracyps, i had one at one time, and ill warn you that they indeed arnt very colorful. this may have been due to him being by himself but like it has already been said they just dont like bright light. these can also be a somewhat costly fish at times, no real aggression issues there.
shellies, ive kept multies as well as brevis. my male brevis killed the female and beat the crap out of the other fish in the tank. i eventually sold him to a friend. mine was an "ikola sunspot", which are really pretty. but i just didnt have a good brevis experience i suppose. they arnt colonial either which is why i love my N. multifaciatus. i have 2 tanks full of them, my breeding colony which i keep in a 10g and my smaller colony which has been moved from tank to tank over the last year or so. when i had them in my 55 i noticed that there were common skirmishes between multies on the outside of the colony and my J. marleri "gombi" (also called J. transcriptus) so i suppose so breaking of the lines of sight would be necessary because i had plenty of rocks for him.
tanganyikan fish are very hard to stock in my opinion because there are so many different species to choose from and each have their own pros and cons and most arnt compatible or else are hit and miss. if you stick with them youll end up with many tanks of them to keep them all lol.
