Fish Behavior Odd

[Jahalu]

About 6 weeks ago I purchased 5 blue chromis. Four immediately schooled together, but I had one who stayed alone at the bottom. Figured it was probably sick etc. However, it’s now been a long time and there’s no sign of disease. It stays in one lower corner of the tank and rises up a little to eat when it’s feeding time. I’m also noticing its appearance is different from the others. It is slightly bulkier and much whiter. It doesn’t seem to move as quickly as the others. Anyway, anyone ever experience something like this? Starting to wonder if it is a different type of fish. Here’s some pictures. Had trouble photographing them since they are so reflective.
lone swimmer:

Others schooling:

 

[moz71]

I’d say he is last on pecking order! Being intimidated by the others. They are known to pick on others to death. I always seem to end up with one. Don’t think it is a different breed

 

[Nemolover12]

I’d say he is last on pecking order! Being intimidated by the others. They are known to pick on others to death. I always seem to end up with one. Don’t think it is a different breed

I agree. I had a 3 chromis together and ended up with 1 left.

 

[wbama387]

Is this common for schools of fish where only one survives? I wanted to do the same with yellow tail damsels but may rethink that if schools do survive.

@Jahalu what size is your tank?

 

[Jahalu]

Thanks for the replies. Not sure there’s much I can do for this fish, then. My tank is 75 gallon.