Will A Regular Skirt Tetra School With Long-Finned Skirt Tetras?

[jvdb]

Purchased 5 long-finned skirt tetras about a week ago.  One of them looked particularly small and the guy at the pet store was going to net him out for me and replace him when he was catching them for purchase but I told him not to worry about it.  Upon arrival at home I looked a little closer and realized he is just a black skirt tetra, not a long-finned black skirt tetra.  It still didn't bother me, however he seems to be acting a little funny the past two days, hiding in a corner and only coming out mainly to feed.  Still very agile and appears healthy when moving but doesn't want to be near the rest of the group.
 
Do all types of skirt tetra school together, or does my little guy simply know he doesn't belong?  Trying to determine if he is either sick or just lonely, again he appears healthy just segregated.

 

[jvdb]

Today is day three of him hiding out.  He came out to eat this morning, but I think I am going to go exchange him today.

 

[the_lock_man]

Should shoal together fine - it's like the difference between a human with long hair and one with short hair - same species, just looks slightly different.

 

[jvdb]

Should shoal together fine - it's like the difference between a human with long hair and one with short hair - same species, just looks slightly different.

Then maybe he is sick... either way I think he is going back to the store.  I have a two week period.   Feel bad ditching him but would like to ensure I purchased a healthy fish.