Pale Serpae Tetra Not Eating?

[wet44]

Hey, so one of my eight serpae tetras has looked a little more pale and ragged than the rest of my serpaes for a while now, and I noticed today that it was going after the food aggressively but would spit it out immediately after trying to eat it. I used the flake food that I give to my serpaes and neons and all of the others seemed to eat normally. 
 
I have had three of my serpae tetras for a few years, so it could just be getting near the end of its life. 
 
I also occasionally used to feed my fish bloodworms. Could that have anything to do with this? Are bloodworms suitable for serpae tetra, neons, and corys? I know that bloodworms are a treat for once a week.
 
Thanks!

 

[ester]

How many years would you say?

 

[wet44]

Probably 3-4.