Just wanted to add my thoughts
I have 2 albino, 1 bronze, 1 adolfi and a group of 7 julii. Because of various reasons, I've not been able to up the numbers of the albino/bronze (not enough tank space) or the adolfi (Can never find them in shops for under £15 per fish!). They all share a 230ltr, and although they do ok, they are no where near as active as my group of julii, who are constantly hanging out in little groups, or following each other up and down the tank in a long line. I used to think that they would just shoal all together, and they do to an extent, but you can really tell now that they would prefer their own species for company.
I can't wait to split my tank stocking between two tanks so I can up numbers. The julii will be moved to a 180 ltr, and the albino, bronze and adolfi will stay in the 230 ltr, and as soon as it's safe I will be increasing each group to a minimum of 6 (a mixture of bronze and albino for one group, as they are the same species).
I'm not in anyway being critical of anyone else's fish keeping abilities, I only wanted to share my experiences of having low numbers of corydora
