Hardhead Silverside, Atherinomorus stipes
The Hardhead Silverside, Atherinomorus stipes, whose common Spanish name is tinícalo cabezón, is a species in the Old World Silverside or Atherinidae Family, known collectively as tinícalos in Mexico. Globally, there are eleven species in the genus Atherinomorus with only one found in Mexican waters, the species described herein which is found in the Atlantic.
The Hardhead Silversides have elongated relatively deep bodies with a rounded cross section. They are translucent and silvery pale olive in color and have a silver stripe that is narrow at the front, broadens toward the rear, and overlies a black stripe on the sides. Their caudal fin has two series of black dots along the sides; in mature fish, the caudal fin also has a black tip. Their head is wide and relatively deep with a straight profile. They have disproportionately large eyes and a fairly large terminal mouth that opens at the front and is equipped with small teeth set in narrow bands on the jaws. Their anal fin has one spine and 11 to 13 rays and their caudal fin is forked. They have two dorsal fins, the first originating before the anal fin and having five spines, and the second located after the anal fin and having one spine and 8 to 10 rays. Their body is covered with small scales.
The Hardhead Silversides are a schooling pelagic species found in shallow waters over reefs and adjacent soft bottoms at depths up to 35 feet. They reach a maximum length of 10.0 cm (3.9 inches). They are active daytime feeders that consume zooplankton. Reproduction is oviparous with large masses of sticky eggs released by females several times per year; the eggs attach themselves to shallow water seaweed via long filaments and are then fertilized by males. The larvae are planktonic.
In Mexican waters the Hardhead Silversides are found in all waters surrounding the Yucatán Peninsula.
The Hardhead Silverside is similar to, and can be confused with, the Reef Silverside, Hypoatherina harringtonensis (silver stripe wide at front).
Due to their small stature, the Hardhead Silversides are of limited interest to most. They are used on a limited basis as bait fish. They are also an important food source for a wide variety of fish, marine mammals, and sea birds. From a conservation perspective they are believed to be common and widespread, thus classified as of Least Concern, however, their population status and trends are unknown.
Hardhead Silverside, Atherinomorus stipes. Fish caught in coastal waters off Islamorada, Florida, December 2013. Length: 5.1 cm (2.0 inches). Catch, photo, and identification courtesy of Ben Cantrell, Peoria, IL.