small open water african ciclids/fish?
 

are there any small open water fish(not nessacerly ciclids)that could be kept in a 30g long with a julie pair and a shelldweller pair which it currently contains. both take up habits that leave the largest part of the tank un-occupied

Try giant danios, silver dollars, or Australian rainbows. Any of these fish are large enough and fast enough to escape any attacks by your pugnacious cichlids. Many people use these fish as "target fish" to temper the aggresion of cihlids in home aquariums. It may seem cruel and inhumane, but as noted previous, the "target fish" are just too elusive to really be harmed.

silver dollars seem a nice addition will they be able to cope with the very hard water that the ciclids demand? i thoght they were a softwater fish