Or more specifically, Pliny writing on Vedius's aquarium:
"Vedius Pollio, a Roman equstrian, a friend of the emperor Augustus, found that lamprey eels offered him an opportunity to display his cruelty. He used to toss slaves sentenced to death into ponds of lampreys, not because wild animals on land were not capable of killing a slave, but because with any other type of animal he was not able to enjoy the sight of a man being torn to pieces, completely, in one moment."
Pliny the Boss Roman Elder, Natural History 9.39.77
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Etur Bronzemelts, a Dwarf axelord, a friend of the King Vabok, was attacked by the fish recently. She witnessed death by Lamprey recently. She lost a friend to the fish recently. She detests carp for their murderous nature.
Rom Bistkash the human waxworker necromancer, ☼Bootbolts the fish stand up☼. The writing drives on relentlessly and warns of the danger of rivers.
Also of note is that Dwarves are in general fiction around 1.3 meters tall. Lampreys can grow up to a meter in length - Carp can grow up to 1.2 meters in length and up to 65 years old.
"Pike are found in sluggish streams and shallow, weedy places in lakes, as well as in cold, clear, rocky waters. Pike are typical ambush predators; they lie in wait for prey, holding perfectly still for long periods and then exhibit remarkable acceleration as they strike. In short, they will inhabit any water body that contains fish, but suitable places for spawning are essential for their numbers. Because of their cannibalistic nature, young pike need places where they can take shelter between plants so they are not eaten. In both cases it comes down to a rich submersible vegetation nearby. Pikes are seldom found in brackish water, except for the Baltic Sea area. Pike are known to prefer water with less turbidity but that is probably related to their dependence on the presence of submersible vegetation and not to their being a sight hunter."
-Wikipedia on Pikes. They could snatch unwary Dwarf if they believed it to be worth the effort.
Pikes can grow up to 1.5 meters in length.
Is it possible that fish should be re-clawed?
Why don't fisherdwarves use fishing lines?
Did fish from previous DF version worlds learn to actively prey on Dwarf sized animals?
That is a Lamprey Eel's dentistry.