Aquatic Species

RAINBOW TROUTOncorhynchus mykiss

Description –  Silvery trout with pink operculum and a light pink to reddish band along the lateral line. Resident rainbow trout tend to be darker in color than steelhead with a green/brown back that fades downward. Some may have a faint iridescent blue on the side. Rainbow trout and are freckled with black spots along the body and tail, they have a large mouth and well developed teeth.

Native – Seasonal

Temperature – 15o- 18oC growth can live in range 0 – 27oC however <4o and >23oC can be lethal

Ecosystem Role – Predatory, eating mostly invertebrates

Life History – Nonanadromus  trout reach sexual maturity between 2-3 years of age. The female will dig a redd in 1-13cm gravel where upwelling is good and lay between 200 – 12,000 eggs depending on her size. The adjacent male will immediately fertilize the eggs, warding off interlopers where possible.  Both fish will leave the nest and fry can be expected to emerge from the gravel in 5-6 weeks.

About the Trout – There have been many discussions surrounding the native status of Resident Rainbow Trout in the Kings River of the foothills of Fresno County. Most research indicates that prior to the 1930’s coastal steelhead would swim up via the Tulare Lake Basin or Dutch John Cut in intermittent high water years. As temperatures in the region would warm and waters slowly recede the trout would either return to the ocean or assume residency in the higher waters of the Sierra. In later years resident rainbow trout inhabited the area above what is now Pine Flat Reservoir, with a small population reported near the town of Piedra. Prior to the construction of Pine Flat Dam permanent populations of resident rainbow trout in the area are considered to have been negligible.  Many locals have memories of abundant wild trout in the lower Kings River however these great events were seasonal and infrequent at best.  Stocking numbers were much higher prior to the mid-1980’s, further contributing to the perception of a hearty rainbow trout population in what is now the tailwater fishery. The hydrogeology, elevation and climate of the region is indicative of a sucker, roach, pike assemblage and may be stressful in drought years for rainbow trout during hot valley months.

Evidence has shown that a small population of rainbow trout will hold over from year to year even during difficult climatic events. As such, the KRFMP engages in habitat projects, management strategies and use of our donated cold water pool to enhance and improve the habitat and propagation of rainbow trout in the region. Paired with enhanced stocking from the San Joaquin Hatchery, rainbow trout can remain part of this low-elevation assemblage for all to enjoy.


THREE-SPINED STICKLEBACK  (Gasterosteus aculeatus)

Description – Small flat-bodied, scaleless fish with armored plates covering the area just behind the eye to the pectoral fin. Stickleback have large eyes and terminal mouths. Bodies can be almost diamond shaped ending in a small caudal peduncle and rounded tail. Their name comes from the three distinctive bony spines located in front of the soft dorsal fin. They also have a thick bony spine on each side which serves as the pelvic fin.

Native – Yes

Temperature – Prefer temperatures below 23 – 24oC

Ecosystem Role – Specialized feeders (chironomid midge and ostracods). They are bite sized for many wading birds and larger fish so long as the stickles don’t obstruct swallowing.

 Life History – Small predatory fish, three-spine stickleback spend most of their time shoaling in loose groups in clear slow moving water. As visual predators good water quality is essential for survival however they can withstand highly saline conditions. Males build a nest in the sand near vegetative cover. A female stickleback will lay between 50 – 300 eggs over multiple spawns, with the males chasing them off as soon as the eggs are deposited. The male will protect the nest and babysit the young until they begin dispersing and become too difficult to monitor.

CA ROACH (Hesperoluecus symettricus)

Description – Small minnow, generally no more than 10cm long. Relatively large eyes, small mouth and orange fins.

Native – Yes

Temperature – 8o – 35oC adaptive & versatile

Ecosystem Role – Favorite food of the non-native green sunfish

Life History –  Most abundant in mid-elevation streams of the Sierra foothills. Omnivores which generally browse at the bottom of shallower waters with coarse substrates, they can adapt themselves to almost any habitat type where they can withstand the current.  Average lifespan is about 3yrs. Sexual maturity is reached at about 5cm in length.  Will spawn 250 – 2,000 eggs March – July when water temperature exceeds 16oC.

SPOTTED BASSMicropterus punctulatus

Description – Spotted bass look a lot like largemouth bass except for they have smaller mouths and a line of irregular blotchy spots (sometimes diamond shaped) following the lateral line.  Abundant in Pine Flat Reservoir with smaller populations found in the lower river.

Native – No

Temperature – Preferred temps 24o – 31oC

Ecosystem Role – Although bass are a non-native species and the full impact of their presence on native fish is not well known, they are one of the only fish currently in the system  that will frequently target the invasive signal crayfish as prey.

Life History – With a lifespan no longer than 4-5yrs. spotted bass spawn in late spring in shallow slow moving water. Each nest can contain 2,000 – 14,000 young. Males will defend the nest for the first month. Yong of the year tend to shoal in shallow water after leaving the nest. Spotted bass are known to hybridize with other bass species.


SACRAMENTO SUCKERCatostomus occidentalis

Description –    Large minnow with sub terminal mouth and large fleshy lips. Adults tend to be greenish brown on the back and beige to yellow gold on the belly. Young suckers are gray to silver on top with dark splotches on the sides. These fish can grow larger than 60cm with lager fish likely 10 years or older. Females live longer and may grow larger than males. One in Shasta CA was reported to be approx. 30yrs. old.

Native – Yes

Temperature – preference 20o – 25oC however can live in <15o – 30oC

Ecosystem Role – omnivores

“The success of suckers has given them a bad reputation among anglers, who frequently accuse them of competing with game fish for food and space. This accusation is rarely justified. Too often the presence of suckers and the absence of game fishes are considered to be part of a cause-and-effect relationship when, in fact, the lack of game fishes (especially trout) may be due to poor habitat, low water quality, or overfishing. Suckers may even be beneficial to game fish populations as forage fish that utilize food (algae & detritus) largely unavailable to predatory fishes. They also have some importance as commercial and sport fish: they reach large sizes, put up a good fight on light tackle, and are quite edible. They were an important source of food to the Native Americans (Lindstrom 1996). Hubbs and Wallis (1948) pointed out that those in Yosemite Valley preferred Sacramento suckers to trout as food” (Moyle 2002, Inland Fishes of California).

Life History – Reproductive success highest during wet years. Fish are sexually mature between 4-6yrs. of age and can spawn as early as late December.  Spawning can occur at temps 5.6o – 10.6oC. Most spawn in gravel riffles February – early June peaking in March and April.”  – Moyle 2002 (Inland Fishes of California).




Description – Large long-bodied fish with tapered pike-like head, deeply forked tail and large mouth with a maxilla that extends behind the front margin of the eye. Most are silver in color, however larger fish can have dark olive brown backs and golden undersides.

Native – Yes

Temperature –  Lives in regions where summer temps can range from 18o – 28oC

Ecosystem Role – Common food of the Native Americans. Opportunistic predator will seldom pursue small fish during the day. Will feed on the non-native signal crayfish found in the lower river. Pikeminnow feed infrequently due to slow metabolism. Will also eat salmonids and sculpin however not their first choice.

Life History – Common in clear waters of Central California. Prefer low to mid-elevation streams with complex habitat structures. Sexual maturity at age 3-4 or 22-25cm in length. Will spawn at 15o – 20oC. 15,000 – 40,000 eggs per female and can live up to 16+ years.


SCULPINCottus spp.

(Prickly & Riffle species)

Description – Small dark-colored, bottom dwelling fish that are most often found in cobbles, rubble or gravely stream sediment. Sculpin do not have a swim bladder and require high levels dissolved oxygen in their environment. They have large heads and mouths with scaleless bodies that terminate in a small caudal peduncle. They have a prickly dorsal fin in front and a longer softer one in the back. Riffle sculpin have additional spines on the anal fin and prefer faster moving waters than their prickly sculpin neighbors.

Native – Yes

Temperature – Can tolerate temperatures up to 28o – 30oC

Ecosystem Role – Important forage for game fishes. Prickly and Riffle Sculpin can be found co-existing in the Kings River tailwater fishery. “Riffle sculpin almost invariably occur with rainbow trout …  More importantly, sculpins are a good indicator of water and habitat quality; their presence indicates first-class salmonid habitat” (Moyle, 2002).

Life History – “Sculpins are most abundant in coldwater streams, and their presence is usually an indicator of high water quality” (Moyle, 2002). Sculpin are sexually mature after 2 years and spawn March – April and possibly through June. Males will build a nest under a rock crevice and entice females in. A male will mate with multiple females using the same nest.  Each female is capable of laying 280 – 11,000 eggs per season.  Males will guard the nest until the young are able to swim away.



LAMPREYLampetra spp.

(Kern Brook and Pacific species have been described in this river)

Description – Long bodied and eel-like in appearance, scaleless and gray to olive in color. All lamprey in the Kings River measure less than 30cm (most less than 20cm) in length. They have a round terminal mouth with a sucking disc lined with teeth.  They have small eyes and gills that look like a series of small vents that run laterally behind the eye. Are harmless to people and most often found in fines in backwaters or edge habitat. Frequently burrow in the mud.

Native – Yes

Temperature – Can withstand temperatures up to 25oC

Ecosystem Role – largely unstudied

Life History – Kern brook lamprey have a mostly vegetarian diet while pacific lamprey experience a parasitic stage for a few months of life. Both species will spawn in gravel beds and die shortly after.

MOSQUITOFISH – Gambusia affins

Description – Small grey to tan stout bodied fish. Have upturned mouths, a thick cadual peduncle and rounded tail. Males are much smaller than females.

Native – No

Temperature – Preferred range 10o – 35oC

Ecosystem Role – Planted to assist with Mosquito Control by local governments

Life History – Live bearers, they generally reproduce and give birth to between 1 – 315 embryos twice per year. Omnivores and occasionally cannibalistic. Prefer slow to stagnant shallow waters.


All species information was adopted from – Moyle P. (2002) Inland Fisheries of California; Page M and Burr B. (1991) Freshwater Fishes, Peterson Field Guides; the UC Davis California Fish Website and the KRCD Manager of Environmental Programs (onsite biologist).