Arsenobetaine is an organoarsenic compound that is the main source of arsenic found in fish.

[1][2][3][4] It is the arsenic analog of trimethylglycine, commonly known as betaine.

The biochemistry and its biosynthesis are similar to those of choline and betaine.

Arsenobetaine is a common substance in marine biological systems and unlike many other organoarsenic compounds, such as trimethylarsine, it is relatively non-toxic.

[5][6] The compound may play a similar role as urea does for nitrogen, as a non-toxic waste compound made in the bodies of animals to dispose of the relevant element.