1) Found in or near rivers 2) Living in rivers 
living in rivers 
• (a.) Belonging to rivers or streams; existing in or about rivers; produced by river action; fluvial; as, fluviatile starta, plants.
Flu'vi·a·tile adjective [ Latin fluviatilis , from fluvius river: confer French fluviatile .] Belonging to rivers or streams; existing in or about rivers; produced by river action; fluvial; as, fluviatile starta, plants. Lyell. 
living in rivers
fluviatile 1. Inhabiting rivers and streams; fluvial. 2. Of or pertaining to a river or rivers; found, growing, or living in rivers; formed, caused, or produced by the action of rivers.
pertaining or peculiar to rivers; found in or near rivers.