when you start with that many it'll be hard to notice if one or two has gone missing. keep water temp a little low that will help with aggression, put a decent powerhead in the tank to keep them busy would help a bit too. also at small size you need to feed more frequent so they don't turn each other into food. you can probably start moving them after they hit 4" or so.
also you can start cut back on the feeding as they grow so they don't become obesed.
also you can start cut back on the feeding as they grow so they don't become obesed.