Black Or Purple Emperors?

[2polypterus2]

I recently set up a tank for my daughter to enjoy. It is cycyled, 10 gal and heated to around 77 degrees F (can adjust this temp if this is not good?) There is a black background, dark blue gravel, some plastic plants, as well as driftwood and java moss. The filter is a sponge. The one fish in there now is a male betta. I want to get a school of six tetras and i have decided on the emperors. The store has either the purple kerris or the regular blacks, both 6/$24. I have never owned this type of tetra so I was wondering if one or the other would be more suitable for this tank? Also is one species hardier than the other? Thanks for any info you can provide.

 

[Colin_T]

its entirely up to you as they are about the same to keep. Normal emperors get a bit bigger and the males get a filament in the tail. Kerris are a bit small and bluer. They both like the same conditions and do as well as each other.
oh and male emperors have blue eyes and the females have green.