My rosy barb died

[Barry Tetra]

Agree, it is more likely to have been either the Chinese Algae Eater or one (or more) of the swordtails. This is made all the more likely because of the number of fish in the tank size, this overstocking stresses out all of them and increases the likelihood of aggression and disease.

Thanks for info, I will try to remove fin nippers and algae eater.