The grunters are quite variable in their general behavior. Some species are solitary and frequently associate with structures such as rocks, logs, flooded trees, or emergent vegetation. Others form large schools, often up in the water column and over deep water, or hugging the bottom in shallower water. The temperate basses and austral perches are often solitary or occur in small groups, usually in association with structure. At least one species is segregated by sex; female Australian basses (Macquaria novemaculeata) move to the upper reaches of streams, whereas males move downstream. Some species, such as the nightfishes, are nocturnal. Howella move up and down in the water column in relation to night and day. The blackfishes hug the bottom, patrol home ranges, and are active at night. Pygmy perches are often solitary and swim in midwater where they forage for prey or lurk near shelter, such as emergent vegetation. Little is known about the behavior of Chilean perches, but it is presumed that they associate with structure or the bottom. Kuhlias usually aggregate in schools and move in and out of surge zones. Species in freshwater streams often associate with structure or aggregate, as juveniles and young adults, in pools. Snooks and giant perches are often solitary, but may also occur in small groups. Many undertake seasonal migrations into estuaries, usually in relation to patterns of freshwater runoff, but some marine species also migrate into freshwater.
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