ok.. my experience..as a newbie..
i started off with juvies in a 30 gallon.. they were about 2".. i lost 4 due to ammonia (un-cycled tank
once tank was cycled.. i grew them out pretty good.. then put them in a 55.. but now i only have 5 left.. lost 2 more.. over the next couple of months..
then in sept. or so.. i bought 30 plus 1.5 or less.. put them in a 30g.. water changes everyday.. then after a few weeks. split them up into 30 and 29g.. i did notice that the small the fish the more likely they are to death... for what ever reason.. they are very unforgiving due to water parameters..
i know have 11-12 in each tank now. i separated them out by size..
what i learned now..
they take lots of attention... and can die quick.. some grow really fast.. others really slow..
even in same tank.. i understand why discus are not cheap like guppies.. there is LOTS of time and effort.. just to get one good looking fish.. i was naive to think that all fish would grow big and strong!! DUH>> WRONG!!
i probably won't buy anymore fish less then 4" from now on.. i would rather someone else go thru the time and trouble.. of the fish i have left.. i think about 7 are good keepers... the rest.. i will need to get rid of.. the bigger the better.. growing out discus needs lots of space for tanks.. i live in a small apartment.. so i can't expand as i would like..
HOWEVER!! this experience has made me a better discus care giver.. from making their own food, WC, Behavior.. so their are PROS & CONS..
best of luck on what you chose.. i will update my pictures.. to show the growth of my fish.. its been several weeks.. a few of them i am pretty proud of