This article is from the Aquaria: Good (and Bad) First Fish; Breeding FAQ, by Dean Hougen and Elaine Thompson
There are several families of fish from South America, Africa, and
Asia, referred to as Knife Fishes. Many species of Knives get large,
some over 3' long although some of the less attractive species stay as
small as 8". All of them are nocturnal predators, a fact that many a
beginner could have used before all of his or her small fish
"mysteriously" disappeared a few at a time.
 
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