phret-, phreto- +

(Greek: phreatia, a well, a reservoir, a tank; a cistern, a pit)

See this phreat- unit for other closely related word entries.

phreticolous (adjective), more phreticolous, most phreticolous
Organisms inhabiting tanks or containers.
The study of organisms in water tanks.
phretophile (s) (noun), phretophiles (pl)
An organism that thrives in water tanks: Algae is a phretophile that can grow in a tank that holds the water used to flush a toilet.
phretophilous (adjective), more phretophilous, most phretophilous
In biology, descriptive of a life form that develops in water tanks: It is possible to eliminate phretophilous algae from a water receptacle when a person knows the reason why algae grows in the first place.
A plant that lives in a water tank.