Serpae Tetra Aggression?

[mr.waffles1842]

So I bought seven serpaes for my 20 gal high, and theyve been spectacular. Honestly, some of my favorite fish. Yesterday morning, however, 4 of them all looked the same. Small, frayed fins, little color, barely swam. One of my three remaining has a paler color than the other two, and was chased around a lot by one of the serpaes. I am worried that one of the tetras is picking on the others.

 

[mr.waffles1842]

Bump! He's looking worse!!!

 

[Oohitsae]

What's your entire stock list for that tank? I don't think that serpaes are aggressive enough to have done that, but it may have been something else in your stock.