Having to do with rivers
Solution 1:
Consider,
fluvial
Of, relating to, or inhabiting a river or stream AHD
fluviatile
: pertaining or peculiar to rivers; found in or near rivers. Random House
Solution 2:
'Fluvial' or 'riverine'.
fluvial fluvial
(ˈfluːvɪəl)
[a. F. fluvial, ad. L. fluviāl-is, f. fluvius river.]
Of or pertaining to a river or rivers; found or living in a river.
1398 Trevisa Barth. De P.R. xix. lxv. (1495) 901 Yf fluuyall stones ben hette fyry hote and thenne quenchyd therin. 1599 A. M. tr. Gabelhouer's Bk. Physicke 33/2, Iij pintes of fluvial water. 1775 Romans Florida 316 This fluvial expedition. 1867 J. B. Rose tr. Virgil's æneid 190 The fluvial nymphs. 1875 Wond. Phys. World I. i. 39 The descent of fluvial ice frequently causes great disasters.riverine riverine, a. and n.
(ˈrɪvəraɪn)
[f. river n.1]
A. adj.
1. Situated or dwelling on the banks of a river; riparian.
1860 Chamb. Jrnl. XIV. 40 Swampville was in reality a riverine town. 1888 Inglis Tent Life 22 Such villages are common enough in these..riverine plains, all over India. 1898 G. W. Steevens With Kitchener to Khartum 78 Like all riverine peoples he is more clean than bashful.
2. Of or pertaining to a river; resembling a river.
1871 Graphic 29 April 382 The view at high water on the riverine curve is hardly surpassed in any European city. 1876 S. Birch Rede Lect. 24 The riverine navies of Egypt floated to the scene of action. 1884 E. Jenkins Week of Passion II. iv. 156 His face,..deeply rutted, here and there, with expressive valleys and riverine lines of wrinkle. 1898 Pall Mall Mag. May 9 Great riverine improvements..effected at great cost.
B. n. The banks or vicinity of a river.
1895 F. A. Swettenham Malay Sk. 215 All the dwellers on the riverine.
Both from the Oxford English Dictionary. Not that 'riverine' clings to the perspective of a river 'from the bank', although it allows a broader interpretation.
Rivers debouching into the Ocean are also referred at that point (where they are affected by tides and salt water) as 'estuarine'. It is curious though, that there is no well known word particularly associated with fast flowing freshwater. EL&U member 'Eric' has, however, brought to our attention 'lotic' (pertaining to fast moving water), and 'lentic' (pertaining to still water).
Animals that live on, and in, streams and rivers are usually simply referred to as 'freshwater ...'.