Spikedace

DESCRIPTION:
Spikedace are distinguished from other minnows by their slim bodies, oval in cross-section anteriorly (front) and laterally compressed nearer the caudal peduncle (tail origin). The mouth is subterminal, and the snout is pointed. Barbels are absent. The origin of the dorsal fin is well behind the insertion of the pelvic fin. Scales are essentially absent, represented as small, deeply embedded plates visible only after clearing and staining. The first, spinous, sharp-pointed dorsal ray is the strongest. There are 7 dorsal rays and 9 anal rays. The body color is light brown to olive gray above, with bright silvery sides and black specks and blotches on the back and upper sides that coalesce into dark, irregular dorsal pigmentation and an ill-defined, ragged lateral band. Breeding males develop bright brassy yellow on the head and fin bases, a strong yellow to brassy suffusion over the back and sides, and yellow bellies and fins. Spikedace average 1.6 in (4 cm) in length at the end of their first year, and 2.5 in (6.4 cm) by the end of the second. Fish generally live one to two years although some may reach three to even four years.

DISTRIBUTION & STATUS:
Spikedace are restricted to the Gila River basin in Arizona, New Mexico, and Sonora. It has suffered marked reductions in range and abundance over the past few decades and is federally listed as threatened. Its decline has been attributed to habitat deterioration and interactions with non-native species, principally red shiner. Verde River populations are disappearing or perhaps gone, yet others, like that of Eagle Creek, Arizona, persist for a time, disappear for years, and reappear again. Populations in the Gila River, New Mexico, and Aravaipa Creek, Arizona, have persisted continuously with some dramatic year-to-year fluctuations.

HABITAT:
This fish inhabits riffles and runs in shallow flowing waters over gravel, cobble, and sand bottoms. They concentrate in downstream ends of riffles and eddies while Young-of-Year (YOY) inhabit backwaters over silt and sand. The primary habitat for adults consists of shear zones where fast water meets slow water.

FOOD HABITS:
Generally aquatic and terrestrial insects, will feed on fry of other fish during certain seasons. Diet composition is largely determined by, type of habitat and time of year.

REPRODUCTION:
Spawning occurs in spring and summer. Males come into breeding condition as early as April; spawning may continue through June. Breeding males have bright brassy yellow heads and fin bases, yellow bellies and fins. During courtship, males patrol over shallow, sand-bottomed areas, where flow is moderate.

From Minckley (1973), "No territoriality between males is evident, but they seem to remain evenly spaced throughout a patrolled area. Females generally enter the area from downstream, where they are immediately accosted by two or more males. A 'chase' occurs, with the males a little behind and in close contact with the female. The chase terminates when the female either strikes the bottom, or halts, in a flurry of males. All participants then float slowly with the current, then resume their previous activities, or, the female moves downstream, into a pool most of the time, and the males return to patrol."

Females lay approximately 100-300 eggs or more depending on size. Yearling females generally lay one brood per season, whereas two year old and older females may produce two.