Family: Clupeidae
Genus: Dorosoma
Shads are a very important part of many reservoirs. These fish are a massive part of the food chain for larger fish, and make up a huge portion of game fish diet. Shad themselves are actually filter feeders that use gill rakers to sift for plant material and plankton in the water.
  1. Terminal dorsal ray is greatly elongated
  2. Prominent shoulder spot
  3. Anal keel is thin, serrated, or sharp
  4. Deeply forked Caudal fin
gizzard shad
Gizzard Shad

Chad Thomas

Gizzard shad
(Dorosoma cepedianum)
The gizzard shad is an integral part of the food chain in many reservoirs especially Amistad. With a max size of around 20 inches, these fish can get much larger than their local brethren the threadfin, and therefore provide a food base for much larger predators.
The shoulder spot of the gizzard shad should be equal to or larger than pupil in size. The upper surface is silvery blue, transitioning to white on the sides and belly. Horizontal lines may be present in dorsal region. Rounded, blunt snout as opposed to the threadfins terminal mouth.
threadfin shad
Threadfin Shad

Chad Thomas

Threadfin shad
(Dorosoma petenense)
Another of Amistads forage fish, at only 8 inches long, this fish provides the base of the food web for smaller and juvenile gamefish and mid-level predators. These fish are often associated with flowing waters and large schools. Their distribution across the United States is limited due to their intolerance to the cold. They have been known to die as water temperatures drop below 41 degrees farenheit.

The threadfin will have black specks on its chin and the floor of its mouth. Shoulder spot is smaller than pupil or absent in adults. Differentiated from the gizzard shad by its terminal mouth and black specks on the chin.

Last updated: February 11, 2019

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