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CIRCADIAN RHYTHMS IN FISH

Most fish are more active during the day than at night, but there are some species that are nocturnal. Even when fish sleep, they stay alert to potential predators. Fish do not follow a circadian rhythm as strictly as humans do, and are more influenced by food availability, water currents, migration patterns, and whether they are new to their location. the seabed will eat them! Also, it’s a physical impossibility: fish don’t have eyelids. And any cover they find is likely to be tight and scratchy to keep their predators away. But fish do have times they are more active (and you are more likely to catch them) and times they are not (and you won’t catch them). For all but the deepest-feeding deep sea fish, these times can be identified by the tides and phases of the moon. Tides are the up-and-down motions of ocean water caused by the gravitational pulls of the sun and the moon. As tides rise and fall, water flows in and out of estuaries, harbors, and bays, and along the shore. Different locations in inland waters at the same longitude have slightly different high tides and low tides because of the time it takes water to travel through near-shore barriers. The tides change four times a day. There are two high tides, when water levels are highest, and two low tides, when water levels are lowest. High tide occurs approximately six

Get to Know Your Fish

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