Shadow Bass (Ambloplites ariommus)


Department of Wildlife and Fisheries, Mississippi State University, Mississippi State, Mississippi, 39762, USA

  • Fig. 1. Characteristics: Red eye, 4-5 vertical dark brands, Dark band going from the eye to the subopercle, Spiny and soft dorsal and pelvic fins, dark blotches or bands on the fins
    Fig. 1. Characteristics: Red eye, 4-5 vertical dark brands, Dark band going from the eye to the subopercle, Spiny and soft dorsal and pelvic fins, dark blotches or bands on the fins
  • Fig. 2. Distribution of <em>A. ariommus</em> (
    Fig. 2. Distribution of A. ariommus (
  • Fig. 3. Image of Shadow Bass (Ambloplites ariommus)
    Fig. 3. Image of Shadow Bass (Ambloplites ariommus)

Context & Content[+] Expand

Ambloplites ariommus belongs to the family Centrarchidae, order Perciformes, and class Actinopterygii. Actinopterygii is the class of fishes with ray fins and has 14,800 species within the class. The order of Perciforms contains 160 families with over 10,000 species and Centrachidae contains 31 species (Helfman 2009). Common characteristics of Centrachid species are deep or pan-like bodies and dorsal fins comprised of hard and soft rays. Centrarchids are also known for reproductive habits such as nests being build and protected by the males (Helfman 2009).

General Characteristics[+] Expand

A. ariommus is also known by goggle- eye, redeye, southern rock bass, or the most common, Shadow Bass. A. ariommus not only have characteristics of other Centrarchids, but they also have characteristics that make it distinctly identifiable. A. ariommus has dark bands and blotches down its sides including bands and blotches on its fins (Viosca 1936). The markings on the scales of A. ariommus are triangular. These triangular markings make up the bands and blotches on the fish (Viosca 1936). The eye consists of a deep blue pupil and dark red iris for the majority of the year, but during reproduction and courtship, the iris is a lighter shade of red.

Additionally, A. ariommus has a black band angled downward from the eye to the subopercle. Disproportionally compared to its body, A. ariommus has a large head and jaws and is more pronounced in juvenile specimen (Ross 2001). There are eleven hard dorsal spines on the anterior dorsal, and 11-12 rays on the posterior dorsal fin. Both pectoral fins of A. ariommus have 14 rays and there are 9-11 anal fin rays. The Shadow Bass is a medium sized Centrarchid averaging around 10.16 cm in standard length. It has been recorded to be a maximum of 30.48 cm long and up to .45 kg (Ross 2001). Females typically outlive males, but the males grow slightly faster and larger than the females (Cooke and Philipp 2009).

Distribution[+] Expand

Ambloplites ariommus is found throughout the southeastern United States, ranging primarily from western Georgia through Arkansas, Louisiana, and Texas. In Mississippi, it is most common in southern rivers such as the Pascagoula River, Pearl River and also throughout the Mississippi River Basin. Although they are more abundant along the southern border, they have been recorded along the Northeast border near Alabama and Tennessee (Ross 2001).

Populations of A. ariommus are secure in Mississippi, Alabama, and Georgia, but some populations in northeastern Arkansas and southeastern Missouri are vulnerable (Roe 2008). The populations in Tennessee, Texas and Oklahoma are apparently secure. However, research cannot confirm that these populations are in any threat of declining.

Form & Function[+] Expand

The genus, Ambloplites, means blunt armature, and the species, ariommus, means large eye (Ross 2001). The large eyes are characteristic of predatory fishes that rely on sight to catch prey. Fish predators that rely on sight are typically ambush predators, such as the M. salmoides, or the Largemouth Bass. The most similar species to the Shadow Bass is Ambloplites rupestris or the Rock Bass (Ross 2001). The differences between the two species are the shape of the spots on the scales, the amount of rows of breast scales, and the coloration of the ray fins.

A. rupestris has rectangular spots on the scales as opposed to A. ariommus which has triangular spots on the scales. A. rupestris also has fewer rows of breast scales. It has 15-18 rows of breast scales opposed to 21-25 rows on A. ariommus.

Another difference between the two species is that A. ariommus has one more soft fin ray on both the dorsal and the anal fin than A. rupestris (Cashner and Suttkus 1977). The last obvious difference between the two species is the coloration of the ray fins.A. rupestris typically has darker fins, which makes it more difficult to see the band coloration on the fins.A. ariommus, on the other hand, has lighter ray fins which contrast well against its bands on the fins (Viosca 1936).

Ontogeny & Reproduction[+] Expand

A. ariommus typically spawn between January-August, depending on location and temperature. Specimen found in southern Alabama or southern Georgia will spawn earlier due to the warmer water temperature, while those located at higher latitudes usually spawn later once the water temperature reaches the ideal spawning temperature (Cooke and Phillip 2009). Ideal spawning temperature is 17-21C (Roe 2008). Once water temperature becomes ideal, breeding males have distinct darkening of the membranes of the pelvic and anal fins (Cooke and Philipp 2009).
These filaments remain yellow or white in females (Cooke and Philipp 2009). Mature females (maturity is reached at one year) lay approximately 1300 eggs per spawning period; this number varies based on energy investment (Cooke and Philipp 2009).
A. ariommus females will invest more energy into each individual egg after a particularly cold winter, thus producing larger eggs, but in fewer quantities. Conversely, after warmer winters females will invest less energy into individual eggs, producing small eggs in larger quantities (Cooke and Phillip 2009). This adaption allows for the success rate of each spawning period to increase with less dependence on the temperature (Cooke and Philipp 2009).
Because of this strategy, recruitment of A. ariommus is typically consistent. Once hatched, the larvae are approximately 9.7mm in total length (Ross 2001). The larvae also exhibit large melanophores located across the body (Viosca 1936).

Ecology[+] Expand

Because of its unique coloration, the Shadow Bass has adapted to many different water systems. It prefers lotic systems over lentic water systems. It is primarily found in rocky bottom streams and rivers with many boulders and fallen trees (Cooke and Philipp 2009). They prefer this environment, because their dark coloration and bands provide excellent camouflage. However, due to natural selection, their coloration varies across populations. Populations in rocky creeks and streams will have darker coloration, because the lighter colored individuals are more visible to predators. In contrast, populations in sandy streams tend to have lighter colored bands to help avoid predation (Viosca 1936).

A. ariommus are typically found in deep pools of lotic systems and primarily congregate around fallen logs and boulders. Although this is ideal for A. ariommus, they will migrate depending on seasons. As the temperature drops, populations will migrate from lotic systems to lentic systems (Viosca 1936). This occurs, because there is a consistent temperature in lakes and ponds.

Diets of A.ariommus vary based on individual size. Juvenile specimens prefer invertebrates such as mayflies and nymphs, but as it gets larger, the specimen will size select larger invertebrates (Cooke and Philipp 2009). The ideal prey of adult Shadow Bass is crayfish when available. Prey size selectivity of crayfish depends on the individual size of the fish. Larger fish select larger crayfish and vice versa. They do this to try to maximize net energy gain from prey (Cashner and Suttkas 1977). If crayfish are not available, A.ariommus become opportunistic, commonly preying upon small madtoms, darters, and shiners (Cooke and Philipp 2009).

Behavior[+] Expand

There is no information on the subject at this time

Genetics[+] Expand

There is no information on the subject at this time

Conservation[+] Expand

A. ariommus is a secure species throughout the majority of the southeastern United States (Ross 2001). Life history strategies such as energy investment into eggs and the ability to migrate have allowed for the Shadow Bass to flourish within its range (Cooke and Philipp 2009). Due to rapidly changing environment, populations in Louisiana are suffering. These populations are struggling, because they are becoming isolated. This prevents the populations from migrating and integrating gene pools with other populations (Viosca 1936).

Acknowledgements[+] Expand

There is no information on the subject at this time

Remarks[+] Expand

Overall, A. ariommus is a well-adapted Centrarchid that is still mysterious to most of the scientific world. There have been very limited studies conducted on A. ariommus, which leaves many questions unanswered. Of the studies done, the majority of them specify why it is considered its own species and its distribution. There is a lack of research giving substantial insight into its reproduction and courtship behaviors. Future research pertaining to its life history strategies may help solve unanswered questions.

Literature Cited[+] Expand

Cashner, R. C., & Suttkas, R. D. (1977). Ambloplites constellatus, a New Species of Rock Bass from the Ozark Upland of Arkansas and Missouri with a Review of Western Rock Bass Populations. American Midland Naturalist. 98, 147-161.

Cooke, S. T., & Philipp, D. P. (2009). Centrarchid Fishes: Diversity, Biology, and Conservation. 1st ed. 380-381.

Helfman, G. S., Collette, B. B., Facey, D. E., & Bowen, B. W. (2009). The Diversity of Fishes, Biology, Evolution, and Ecology. 2nd ed. 300-301.

NatureServe. 2013. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available

Roe, K. J., Mayden, R. L, & Harris, P. M. (2008). Systematics and Zoogeography of the Rock Basses (Centrarchidae: Ambloplites). Copeia 2008, 858-867.

Ross, S. T. (2001). Inland Fishes of Mississippi. 1st ed. 403-404.

Viosca. (1936). A New Rock Bass from Louisiana and Mississippi. Copeia 1936, 37-45.

Order[+] Expand

Perciformes, also called the Percomorphi or Acanthopteri, are the largest order of vertebrates, containing about 40% of all bony fish. Perciformes means "perch-like". They belong to the class of ray-finned fish, and comprise over 10,000 species found in almost all aquatic environments. The order contains about 160 families, which is the most of any order within the vertebrates.[1] It is also the most variably sized order of vertebrates, ranging from the 7–mm (1/4–in) Schindleria brevipinguis to the marlins in the Makaira species and the heaviest of bony fish, Mola mola. They first appeared and diversified in the Late Cretaceous. Among the well-known members of this group are cichlids, California sheephead, sunfish/bluegills, damselfish, bass, and perch.

Family[+] Expand

The sunfish are a family (Centrarchidae) of freshwater ray–finned fish belonging to the order Perciformes. The type genus is Centrarchus (consisting solely of the flier, C. macropterus). The family's 37 species include many fish familiar to North Americans, including the rock bass, largemouth bass, bluegill, pumpkinseed, and crappies. All are native only to North America.