i think with yours being so small it wont be a "wake up and they are all dead" type of situation, thats usually when they are older. for me it was actually subtly at first because they kept getting bloat one by one and i couldnt figure out why because they are not known for getting this and then i noticed that it was usually the smallest one so the dominant one was harassing and picking on the smallest one till it bloated from stress and then moved on to the next smallest one, etc. the others actually fought a little bit but werent relentless like this little guy was, when i got down to 3 from probably 15-20 fry (all still less than an inch) i divided them each into their own little section and then after a couple weeks thought i would try again to have them all together since my filter was having trouble with two dividers in the tank so i tried that and within the next couple of days he was by himself

he was an awesome little fish though i kind of regret getting rid of him