What are the causes for bottom sitting?

[Jim_D]

What are the things that can commonly cause bottom sitting?

[Mikey]

Water parameters and illness are in my opinion the most common reasons. Others can be that the fish just wants to rest. Mine like to bottom hover/sit at night I've noticed.

[Chai]

Aside from what Mikey mentioned, water temperature, contaminants, overfeeding, and stress (commonly seen in fish that have been through express mail or some sort of tragic event, even spawning).

My koimet bottom sits at night when the lights are all off but only her; she has always done this. My fancies hover above the sand.

Edited May 3, 2015 by Chai

[RanchuDressing]

Also, heavy parasite loads.

[koko]

And sometimes Loneliness, if lets say two fish have been living together for a long time and one passes away... They will mope

[GoldenSpoiledRotten]

To add to the above:

Swim Bladder problems, exhaustion, a female being gravid, a too-heavy tail or wen,

 

... or no reason at all, in some cases. 

[fantailfan1]

Let's not forget certain fish that love to eat their body weight in sand. 

 

Waddles, I'm talking to you. 

[Jim_D]

Appreciate the responses all

[Arctic Mama]

Definitely stress, either from parasites or water quality (those have been the issues in my own tanks over the years). Mine do like to rest on the bottom at night, too, in a low hover.