Picking On Tetras--what Should I Do?

[Elrohirthehasty]

I have a school of 5 lemon tetras and 3 serpae tetras. One of the serpaes is picked on by the other two. It appears that he has fin damage from the harassment. Do you think adding more serpaes would help, even if the new serpaes may be bigger?

 

[Lateral Line]

Serpæ are notoriously aggressive miniature piranha! I would never keep them again. They should always be kept in larger groups, and even then, not with slow moving fish or anything with long fins. If you have the sapce, both species you mantion should be in groups of 6 ideally more, and in the case of Serpæ, better with considerably more.