adj. (Greek υδροβιος hydrobios "water life": hydro-, "water" + bios, "life".)

Living or dwelling in water, or in the vacinity of water; dependent upon a water environment for survival; aquatic.

Examples:
hydrobious fauna http://utenti.lycos.it/bufo2000/morbe3.htm
hydrobious tadpole http://www.gwywyr.com/texts/gems.html