OMG! How adorable! Never saw them this small before! I thought the one I got was small enough! Best of luck for these babies, and I am curious too where did you get them I would love a shoal of these guys!
My advice is good filtration, well originated water. I have mine in a 20 long, there is a 20gal filter on it and a small canister filter for a 10 gallon running on it, also an airstone for added oxygen. My ph is at 6.8 and the temp is 79 degrees. He is getting bigger by the minute it seems! I'll be transferring him into a 150 gallon tank in a month.
Mine would fight with each other most of them will most likly be blind or have one eye, there not a good shoeing fish. And for as much money you will be spending on getting all of them and feeing them, I would just find one large one some ones is willing to sell on here. But that's just me. Make sure to keep the tank super clean, they arnt as hardy at this size as they are larger.