you are getting some terrible suggestions for a 30G tank - - GT, JD, Managuense ??? - - so either people are punking you or they don't get the part about the 30G tank 
IMO, you really ought to stick to fish that stay 5" or less . . . a pair of Convict, Firemouth or Rainbow cichlids would do well . . .
if you want a solitary "wet-pet", how about a single male convict? they can can be quite personable, and won't outgrow a 36" wide tank . . .

IMO, you really ought to stick to fish that stay 5" or less . . . a pair of Convict, Firemouth or Rainbow cichlids would do well . . .
if you want a solitary "wet-pet", how about a single male convict? they can can be quite personable, and won't outgrow a 36" wide tank . . .

