What fish would you add to each classification?

Ken Jones

Staff member
Type of Fish

Everyone agrees that some fish bite better at different times of the day or night but rare is the discussion of crepuscular, diurnal and nocturnal species.

Crepuscular — This is a term used to describe fish that are primarily active during the twilight hours, dawn and at dusk. The word itself is derived from the Latin word crepusculum, meaning “twilight.” However, some crepuscular fish are also active on a bright moonlit night and some fish described as nocturnal are actually crepuscular in nature.
The patterns of activity are thought to be an anti-predator adaptation. Many predator fish forage most intensely at night, while others are active at mid-day and see best in full sun. Thus the crepuscular habit may reduce predation. Additionally, in hot areas, it may be a way of avoiding thermal stress while capitalizing on available light.
The most common crepuscular fish in SoCal and CenCal are probably Pacific mackerel, which often present a “hot” bite during the early morning and evening hours while being virtually absent during the day. To be fair, the mackerel also sometimes bite well into the night when anglers use glow sticks to attract the mackerel and keep track of their line when they hook up a mackerel.

Diurnal — This term describes a fish that is most active during the daytime and rests (or even go to sleep) during the night.
A study at Catalina revealed a number of species that fell into this classification. The fish included topsmelt, kelp bass, opaleye, halfmoon, kelp perch, shiner perch, pileperch, black perch, blacksmith, garibaldi, California sheephead, senorita, rock wrasse, giant kelpfish, several smaller kelpfish and several species of gobies. Although I have caught a few of these at night I have never seen a sheephead, senorita, or rock wrasse caught at night; all reportedly sleep at night.
Interestingly kelp bass behavior differs with age. Juveniles feed on zooplankton during the day and shelter among vegetation at night. Sub-adult kelp bass feed mainly on the bottom during the day (on things like crustaceans) and many do not feed at night (depending upon location). Adults are much more piscivorous (feeding on fish) and though primarily crepuscular often feed throughout the night.
Many would list halibut as a diurnal fish even though a few are caught at night. Some argue that the reason they are not caught at night is that few fish for them at night.

Nocturnal—These fish often sleep or are fairly inactive during the daytime but are active at night, thus the opposite of diurnal behavior. Nocturnal fish generally have a highly developed sense of hearing and smell, and specially adapted eyesight.
Fish commonly seen as nocturnal include California scorpionfish (commonly called sculpin), olive rockfish, kelp rockfish, treefish, salema, black croaker, queenfish, yellowfin croaker and walleye surfperch.
Almost all sharks and rays are most active at night although they also may be seen during the day. Thresher sharks are an exception primarily feeding during the daylight hours.


Well-Known Member
What I have experienced: Jack Mackerel and Pacific Mackerel day and night, Sardines daytime, Bonito daytime, Calico bass day and night, but night time is when the big ones come out to eat, as is Barred sand bass and Spotted bay bass. Halibut do feed at night, but is more active when there is moon light available, or when there is a Grunion run, California scorpion fish day and night, Grass rockfish mainly at night. Yellowfin croaker can be very active in the daytime, as is queenfish and salema, and walleye surfperch and surfperch.
Do foggy days like the type in the San Francisco Bay that can last till 12:00 or overcast days affect the feeding habits of the fish.


Active Member
Interesting topic. A couple of thoughts.
Lunar cycle plays a part.
I would think that halibut would be daytime feeders primarily because they are sight feeders-but every creature is an opportunist.
I think that tidal action has a big influence on this. Rockfish, I think, are more influenced by tides than day/night feeding.
Freshwater fish are easier to divide into these categories.

Ken Jones

Staff member
With a few exceptions, i.e., sheephead, senorita and rock wrasse, I have caught almost every species at different times of the day/night. However, there is no doubt that many fish are more active and have a preferred time for feeding. The best example is sharks and though almost every species can be caught during the day almost all are more active at night. And for the mackerel, although they will sometimes bite all through the day and night, it's very common to see a good bite at daylight followed by slow action during the day and then a renewed bite at dusk. I think very few of the fish fit a classification 100% of the time but I think many fish do have "most active" times.