is this that rare murderous African Blue Tetra???

[Magnum Man]

that @GaryE has talked about in the past ... "they" say's it gets to 5 inches at maturity...

https://www.dansfish.com/product.detail/3595/Long-Finned-African-Tetra-(Brycinus-longipinnis)

Brycinus longipinnis – Long-finned Tetra — Seriously Fish

www.seriouslyfish.com

 

[GaryE]

Nah, that's its short finned cousin who became a kind and gentle social worker. This other thing was blue with superlong filaments, which they destroyed on each other as soon as they met.