Bleaks associate in large shoals: at certain seasons, they tumble about near the surface of the water, are incapable of swimming with any rapidity, and appear to be in great agony: they, however, speedily recover, and disappear. -Fish, thus affected, are denominated mad bleaks. They are likewise troubled with a species of gordius, or hair-worm, which often proves fatal among them.
The Bleak is reputed to be a delicate fish, though it is chiefly valued on account of its scales; which, by treating them in the manner already stated, vol. iii. p. 357, may be manufactured into Artificial Pearls.