I got 6. They will get around 2.5-3 inches so figured 6 may be a good number for a 55 gallon. They also have 6 cherry barbs in there too.They do look boyish, redder red & blacker black. Whee, that 1 looks tiny...& maybe male? Do you chop up some bloodworms for him? He needs to catch up...
How many did you get?