Minnows and Carps
Genus: 3 or more
Across the world there is a huge variety of fish in the family Cyprinidae. Frankly, they can be very hard to tell apart even with an experts assistance. So don’t feel bad if they are difficult to identify. They're found across all sorts of rivers and lakes are most likely what you're seeing swimming around on the banks of your local lake.
This recognizable minnow is found in both small and large moving streams throughout every drainage in Texas. Female blacktail shiners have been observed making mating calls to attract males, but despite this, often end up hybridizing with red shiners, in part due to their indentical spawning season, April through September.
The blacktail gets its name from its distinct black spot before the base of the caudal fin, which is usually larger and more prominent than other local minnow. It has a visible lateral line that curves down.
Research has shown that red shiners are most numerous where few other kinds of fish occur, likely due to their high tolerance for harsh conditions. Although widespread, tolerant, and highly invasive, red shiners have declined sharply, possibly due to habitat modification and predation. They have been extirpated (removed) from many of the ecosystems they once invaded.
Red shiners have a purple triangle shaped bar above pectoral fins, and behind their opercle. Dark pigment surrounds dorsal scales, and breeding males have bright red fins.
This small silvery minnow is usually found in relatively large and tight school in fast moving streams and rivers. They mostly feed on aquatic insects and algae that they pick out of the water column. Some estimates indicate as much as 75% of their diet consists of these two sources.
The texas shiner has dark melanophores that line the terminal mouth. Its eyes are larger than its snout, and it has a dark mid dorsal stripe (running along the top ridge). The midlateral stripe is faint, and seperated from the dorsal pigment by a clear, light colored stripe.
This species has long been on the list of endangered fishes, mostly due to introduction of non-natives to its natural habitat. Most recently it has seen increases in population in Big Bend and the Rio Grande, but in Amistad, the fish still struggles to find a “fin” hold.
A black midlateral stripe ends just before a black spot that lies just beyond the caudal fin base. The midlateral strip is often faded toward the head and more visible toward the tail. You can often see the lateral line curve down through the midlateral stripe as well.
This species is widespread across the east coast, and can be found locally within the Rio Grande and Big Bend, as well as much of the Edwards Plateau. Due to their tolerance for low oxygen, their favorability of dry foods, and ease of travel, these shiners are ideal for scientific research and bioassay.
Sand shiners have a dark mid dorsal stripe and a visible lateral line that is dark and double dashed. Their mid lateral stripe will curve slightly upward at the base, or be straight, following the lateral line. May sometimes possess a triangular caudal spot.
Manantial Roundnose Minnow
The manantial round nose is sympatric with the devils river minnow. This means that they were originally a single interbreeding population that was separated (likely by some very complex climate and geology related event). After an extended period of seperation, they evolved into two distinct, non-breeding species before being reunited.
Much like its sympatric species, the manantial round nose also has a small black spot before the base of the caudal fin, but it is much smaller. It also has a dark midlateral strip running the entire length of the body, and no melanophores lining its scales.
Devils River Minnow
Endemic only to the devils river and a few nearby waterways, this small fish is now considered critically endangered. Due to the reduced spring flow of the Edwards aquifer, introduction of species like the armoured catfish, and a drop in water quality, the Devils river minnow is struggling to maintain a healthy population. There are many efforts to help maintain their population, many of which have positive lasting effects on other at-risk species
Can be differentiated from the manantial roundnose minnow by the dark melanophores that surround its diamond shaped scales. The caudal spot is also wedge shaped instead of round.
If this fish looks familiar, it's because it’s the most popular bait fish in North America. And that is very likely why it is here in Amistad. Bait release has led to it being one of the most widespread species within the continental U.S.
The golden shiner has a black midlateral stripe in juveniles that fades in adulthood. Its lateral line curves down very deeply. It has a unique terminal pointed mouth, as well as a longer anal fin, and more rays than local shiners. Max size can reach larger than many similar species, as much as 14 inches.
The suckermouth is not often found in the gulf slope drainages of Texas, but can be found readily in the Pecos drainage. Primarily including insect larvae, and detritus. These fish are usually found in high current lakes and rivers, probing the substrate to find food. They are often used as bait fish in northern states.
Suckermouth minnow possess a rounded snout with eyes positioned high on the head. Their mouth will always be inferior (as opposed to the subterminal bullhead minnow). Most will have a dark midlateral stripe that ends with a small caudal spot (usually square in shape).
Commonly used as a bait fish across the U.S., the bullhead minnow will often serve as a large portion of gamefish diet as well. While these fish are excellent tank fish, they are not often used for research purposes as they get nerves easily.
Bullhead minnow always have rounded snouts, terminal or subterminal mouths, and a midlateral stripe that forms vaguely near the head and becomes finer toward the tail. It should end just before a faint caudal spot. Dorsal fin often hosts a black blotch toward the head.
The central stoneroller gets its name from its feeding behavior. They can often be seen travelling in schools using their cartilaginous lower jaw to feed on algae and small particles on stones. These fish are most often found in the drainages of the Edwards plateau,but can be found as far west as the Devils River.
The central stoneroller has a blunt rounded snout. It will also have a somewhat dark midlateral stripe that runs to a caudal spot but can be absent in adults.
The Gray Redhorse, like many bottom feeding fish, has been plague by habitat degradation for years. This species, however, persists in systems disturbed by low-head dam and reservoir construction due to their opportunistic feeding strategy which allows them to adapt to systems such as Amistad.
Breeding males will have orange and yellow fins. Gray redhorse should also have dark black membranes between rays on the dorsal and caudal fins. They will have an inferior mouth as well.
These fish are primarily benthic feeders, meaning they feed at the lowest depths of the system they inhabit. Their most common food sources are plankton, rotifers, and algaes. They usually prefer sandy or muddy substrates, and turbid waters, but can be found in fast moving and clear stream as well.
The river carpsucker should have a distinctly triangular subopercle corner, just above the pectoral fin. It also has a completely inferior mouth, differentiating it from the smallmouth buffalo.
This fish most commonly consumes zooplankton and algae, but have been known to feed on small crustaceans, larvae, and diatoms. Due to its rapid rate of growth early in life, this fish is commonly used as a farm fish. It is used for human consumption as well as farm feed across the U.S. It can be found across most of the country, but here it will most likely be found in fast moving streams of the Pecos and Rio Grande.
The smallmouth buffalo is differentiated from the river carpsucker by its rounded opercle and sub terminal mouth.
This fish is widely regarded as one of the most invasive fish in North America. Introduced to the U.S. in the 1870’s, it has spread across much of the southern United States today. While most western states have seen numbers drop, it can be found statewide in Texas. The carp is a harmful species as it is notorious for disturbing substrates and kicking up particles while feeding, which can cause problems for many varieties of aquatic life.
Mouth can be terminal on juvenile carp, and can have short barbels on either side.
Last updated: February 12, 2019