i calculated your dimensions out to be 187.01 US gallons, so you could probably 10 at the most, but you must have some heavy filteration, and a well aquascaped tank to spread out territory.
Without casualties, constant bickering etc, probably just a pair or possibly a small group of some same sex singles full grown ...really depends on which ones youre asking about.
V. fenestrata,V. guttulata, V. zonata, V. hartwegi, V. bifasciata, V. breidohri, V. argentea, V. regani, V. melanura, V. synspila, and V. maculicauda, V. intermedia, V. godmanni, and V. microphthalma, V. heterospila and V. tuyrensis
I dont think its vieja anymore either...or it wont be for much longer, but who knows. taxonomy is always changing.