hi, i recently bought 2 corydoras julii for my community tank. i know they should be in a group of 5 or more. a while back i had 4 sterbai who died within a few days of buying them. no apparent reason and the water parameters were fine. i since changed the gravel to sand and the tank was fine over the last couple of months so i thought i'd try again, starting with 2 fish. so far so good. i would like to add another 2 or 3 corys in a couple of weeks/months and am wondering if i should stick with juliis or if i could mix my jullis with sterbais. would they shoal even though they're diff breeds? thanks for any advise as i'm new to corys