It just depends on how many you get.I have seen them do fine in a 20 gal tank,but if it were me I would put them in at least a 30 gal tank.They are a real active fish and swim around alot.They also like places to hide out also as they can be a bit aggressive with eachother over territory and a 20 is sometimes just not big enough.Beautiful and fun fish to watch.what size tank does the Metriaclima Aurora requier?