I have a small school of 5 black neons in my aquarium. 3 are absolutely huge, while other other two stay petite....and I think I know why. The three big ones are pigs and will eat anything, including the oto's algae wafers. The three are unbelievably bloated every morning after I feed algae wafers, but the other two eat very little of them or none at all. I usually don't feed that day because I'm afraid they'll explode! So they smaller ones don't really catch up. I used to think that they were the two males of the bunch, but I don't think size is that much of a difference. One of the small ones is my first ever that I got a year and a half ago, and the other is my newest that I got only a month or two ago. They are both the most submissive, but I think that just has to do with their size. When I'm feeding them flakes, they all get a pretty even amount and no one is chased away because they are all pre-occupied. Should I just feed them more?

Some tetras will stay smaller than the others. Are the two runty ones bought at a different time to the others? Could be genetic.
As long as they are healthy then dont worry about them Kissy.

As for them eating the algae wafers, put them in an hour after its gone dark and they shouldnt bother with them.

Tell the three pigs that! They hear me open the hood and snap awake lol. The other two seem like they are still healthy and active, so I'm not going to be worried.

LOL, well, maybe half a wafer at one end and another half at the other.
The little piggies