It's hard to say...I had a load of pond snails in my 55 for a while (stupid hitchhikers) and after about a month or so they all seemed to disappear except for the empty shells. But I can't tell if it was both my multis and julies or just the julies...I wouldn't risk getting something that you really like.
And don't bother finding juvies. Honestly, if you get a trio, you are bound to get a pair IME...and they will start breeding in no time.