I first saw them in the late 70s, early 80s, but soon after that they seemed to disappear.
They lost favor quite a few years ago, because when put in a community tank, they usually killed all other fish, even those much bigger than themselves.
Or if put in a species only tank, one usually killed and ate, even as a juvie, all its brothers and sisters.
For years they were also confused with H elongates (AKA the 5 star general) that has a similar disposition.
They reach about 10" (the Nile river location variant) and many aquarists were put off ending up with one 10" fish in a large tank,