If it really comes to this
http

/www.seriouslyfish.com/profile.php?genus=Melanotaenia&species=trifasciata&id=835
http

/www.seriouslyfish.com/profile.php?genus=Melanotaenia&species=boesemani&id=811
Seriously fish one of the best profile sites on the net written by a lot of the best fish keepers and collectors (meaning those that collect them in the wild) in the world - a lot of the other profile sites I read and hold in regard dont often state tank size because its often down to common sense.
Even by the practical fish keeping concept on how to choose a tank size for a fish which states 6 times the length of the fish and 2 times width for the length of the fish - so in this case yeah okay it comes to 30 inches x 12 inches BUT that is the middle point its always stated as going above this for active fish like barbs and rainbows etc but at the same time the stocking rule gets shrunk for less active fish like some catfish (ie banjos etc) and often plecs.
But at the end of the day its not about what this website says and what that website says its just common sense if you want to justify putting a highly active schooling group of 5 inch fish in a 20 gallon tank (taking the smaller sizes you say is okay) then go ahead the fish are going to be cramped in end of story.
I agree bigger is better but there is no point in getting stupid about these things we are clearly not going to agree and I refuse to accept you as right because its just a joke.