Sheepshead Minnow

Diet and feeding

The FishTraits compilation records these diet categories for this species: algae or phytoplankton; detritus or unidentified plant material; invertebrates or larval fish. These are broad categories, not a claim that every individual consumes every example in a category.

Reported feeding positions include bottom feeding. The compilation combines published observations; diets can vary with age, locality, and available food.

Habitat preferences

Reported habitat associations include still-water habitats.

The source records associations with sand, vegetation. An association indicates reported use, rather than an exclusive requirement.

The species is classified as tolerant of a broad range of salinities. This flag does not specify a salinity range for aquarium care.

Reproduction and parental care

The compilation reports a representative maturity age of 1 years. Its maturity field summarizes mean, median, or modal estimates, usually for females; male estimates can be used when female data are unavailable. It is not a fixed age at which every fish first breeds.

Recorded spawning months are Apr, May, Jun, Jul, Aug, Sep, Oct for the source’s reporting region (AL). This is a regional calendar, not a range-wide schedule.

Size and recorded longevity

FishTraits reports a maximum total length of 9 centimetres. Some entries use an estimated asymptotic length; this value should not be treated as a certified record catch.

Recorded longevity in the compilation is 3 years. Wild observations were preferred, but captive records were accepted where wild records were unavailable, and unspecified records were assumed wild. The value is not a guaranteed wild lifespan or an aquarium life expectancy.

Native range

Coastal waters from Massachusetts to northeastern Mexico. Also in West Indies (Page and Burr 1991).

Introduction history

Initial introductions were presumably the result of bait-bucket releases (Stevenson and Buchanan 1973; Kennedy 1977). The species was first found in Lake Balmorhea in the 1960s (Stevenson and Buchanan 1973) and in Leon Creek in the 1970s (Kennedy 1977). Hubbs (1980) suggested that its appearance in Leon Creek may have resulted from a water change that took place at a highway bridge crossing during the transport of live bait from the Gulf Coast to the Pacific Coast. Kennedy (1977) suggested that it was probably introduced by local fishermen or bait dealers. The species first appeared in the Pecos River proper between 1980 and 1984 (Echelle and Connor 1989). Wilde and Echelle (1992) believed that Lake Balmorhea could have been the source of C. variegatus introduced into Leon Creek or the Pecos River proper; however, the researchers could not rule out the possibility that the species was introduced into these waters from elsewhere. Based on results of their electrophoretic study of fish taken from the Pecos River proper, Wilde and Echelle (1992) suggested that hybrids are widespread as a result of intradrainage dispersal and artificial transport of hybrids rather than multiple introductions of C. variegatus. Their data also suggested that the initial introduction of this species into the Pecos River probably occurred in the vicinity of Pecos, Reeves County, Texas, and hybrids subsequently dispersed both up- and down stream. However, recent research suggests that Red Bluff Reservoir was the original site of introduction (Childs et al. 1996). This species was not found in subsequent collections in Washington state concluding this introduction failed to produce a breeding population (Greenfield and Grinols 1965).

Ecological impacts

Introduced Cyprinodon variegatus are known to hybridize with other native Cyprinodon species, including the endangered Commanche Springs pupfish C. elegans (Stevenson and Buchanan 1973), the Pecos pupfish C. pecosensis (Echelle and Connor 1989; Wilde and Echelle 1992, 1997; Childs et al. 1996; Echelle et al. 1997), and the endangered Leon Springs pupfish C. bovinus (Minckley et al. 1991; Echelle and Echelle 1997). Hubbs et al. (1991) stated that C. pecosensis is nearly extirpated in Texas due to introgressive hybridization with introduced C. variegatus. Wilde and Echelle (1992) reported that hybrids between introduced C. variegatus and Pecos pupfish C. pecosensis have replaced endemic Pecos pupfish in a 430-km stretch of the Pecos River and have dispersed into downstream areas well outside the recorded range of Pecos pupfish. They concluded that hybridization with C. variegatus had reduced the range of the Pecos pupfish by 60 percent. Because the appearance of C. variegatus was likely the result of a bait bucket introduction involving few individuals, it serves as an example that a small number of individuals can have a dramatic effect on another species (Echelle and Connor 1989). Introduction of C. variegatus into a spring-fed watercourse of Diamond Y Draw in the 1970s rapidly led to extensive hybridization with the endemic C. bovinus and local genetic swamping of the native species (Hubbs 1980; Minckley et al. 1991). The hybrids were eradicated and the native species was restored to the area (Hubbs 1980). Subsequently, however, C. variegatus was again introduced to the area, and this led to genetic introgression of the entire wild population of C. bovinus (Echelle and Echelle 1997). In contrast to the high levels of genetic introgression resulting from introductions of C. variegatus into the ranges of the other two species of pupfish endemic to the Pecos River drainage, Echelle and Echelle (1994) found little evidence of genetic introgression after more than two decades of contact between C. elegans and C. variegatus.