Endangered SpeciesA branch of The Humanity Project

Fish and Aquatic Life

Fountain Darter

Etheostoma fonticola

A thumb-sized fish living only in the Comal and San Marcos spring systems of central Texas, dependent on constant spring flow.

Illustration of a fountain darter ambassador — a small reddish-brown mottled fish with large eyes and delicate spotted fins — resting among green aquatic plants in a clear spring-fed river.
Illustrated Species Ambassador — original artwork, not a photograph

Illustrated Species Ambassador

Dart — Fountain Darter

I'm Dart, an illustrated ambassador for the fountain darter. I am about the length of your thumb and I live in two Texas spring systems, nowhere else.

One fact worth knowing
The fountain darter is one of the smallest darters, living only in the Comal and San Marcos spring systems of central Texas.
What I depend on
I depend on continuous flow from the Edwards Aquifer that holds the water near 70 to 75 degrees all year, and on native plant beds to hide and spawn in.
My greatest threat
My greatest threat is the loss of spring flow from aquifer pumping and drought.
One way you can help
When tubing or swimming the San Marcos and Comal, stay on the marked paths and out of the vegetation beds, and never release aquarium plants or animals into spring water.
Freshwater species at risk →

This ambassador is an original illustration created for this project. It is an educational character, not a documentary image, and its statements follow the sourced record on this page. Artwork and rights record

Why this species matters

The fountain darter is one of several species that exist only because the Edwards Aquifer keeps flowing. Its fate is bound to how much water central Texas pumps, which makes it an unusually direct link between household water use and extinction risk.

If it disappears: Losing it would signal the failure of the Edwards Aquifer spring systems, which also support Texas wild rice, the San Marcos salamander, and the Comal Springs riffle beetle.

Conservation status

IUCN Red List
VulnerableLast verified 2026-09-08
U.S. Endangered Species Act
EndangeredListed 1970, with designated critical habitat.Last verified 2026-09-08
Texas
Endangered (state listed)Last verified 2026-09-08

Population

Locally abundant within suitable vegetation in both spring systems, with population density monitored by regular dive surveys rather than a total count.

Trend: Stable

As reported: Edwards Aquifer Habitat Conservation Plan biological monitoring, ongoing

Source: Edwards Aquifer Authority; U.S. Fish and Wildlife Service

Uncertainty: Local abundance can be high while extinction risk stays severe, because the whole species depends on two spring systems continuing to flow.

Historical: The Comal population was extirpated during the drought of the 1950s when the springs stopped flowing, and was later re-established from San Marcos stock.

Fragmentation: Two spring systems, roughly 20 miles apart, with no natural connection.

Range and distribution

Historic range: Comal Springs in New Braunfels and San Marcos Springs, Texas.

Current range: The same two systems, plus a refugia population held at the San Marcos Aquatic Resources Center.

Range contraction: The natural Comal population was lost once already and had to be re-established.

Regions occupied

  • Comal County, Texas
  • Hays County, Texas

Habitat

Primary habitat: Clear, constant-temperature spring runs with dense mats of aquatic vegetation and algae.

Breeding habitat: Eggs are deposited among filamentous algae and aquatic plants.

Feeding habitat: Feeds on tiny aquatic invertebrates within the vegetation.

Critical habitat: Critical habitat designated in the Comal and San Marcos systems.

Habitat dependencies

  • Continuous flow from the Edwards Aquifer
  • Water temperature held near 70–75°F year-round by spring discharge
  • Native aquatic vegetation such as Texas wild rice and fountain plants for cover and spawning

Biology and ecology

A small predator within a spring ecosystem containing several species found nowhere else.

Important adaptations: Year-round breeding is possible because spring water temperature never varies seasonally.

Size
About 1 to 1.5 inches — one of the smallest darters.
Weight
Negligible.
Lifespan
Roughly 1–2 years.
Diet
Tiny aquatic invertebrates, especially copepods and midge larvae.
Reproduction
Spawns year-round in constant-temperature spring water.
Offspring
Small numbers of eggs laid repeatedly rather than in a single clutch.
Breeding frequency
Continuous.
Age at maturity
A few months.

Primary threats

  • Groundwater pumping

    Aquifer withdrawal for municipal and agricultural use reduces spring discharge; if flow stops, the habitat ceases to exist.

  • Drought

    The Comal Springs stopped flowing entirely during the drought of record in the 1950s, extirpating the local population.

  • Invasive species

    Introduced aquatic plants, snails, and a non-native gill parasite affect darter habitat and health.

  • Recreation impacts

    Heavy tubing and swimming use damages the aquatic vegetation the fish depend on.

  • Water quality

    Urban runoff into the spring systems degrades habitat.

  • Sedimentation

    Silt smothers the vegetation mats used for spawning and cover.

Conservation and recovery

Programs and efforts

  • Edwards Aquifer Habitat Conservation Plan, a regional agreement guaranteeing minimum spring flows
  • Refugia populations maintained at the San Marcos Aquatic Resources Center
  • Native aquatic vegetation restoration in the spring runs
  • Invasive species control and recreation management

Protected areas

  • Landa Park spring run, New Braunfels
  • Spring Lake and the San Marcos River headwaters
  • Designated critical habitat

Legal protections

  • Endangered Species Act
  • Designated critical habitat
  • Edwards Aquifer Authority pumping limits

Measurable progress

  • The Comal population was successfully re-established after extirpation
  • The Edwards Aquifer Habitat Conservation Plan is a working model of regional water sharing for endangered species

Continuing challenges

  • Regional water demand keeps growing
  • Drought of record conditions would again threaten the Comal system
  • Recreation pressure on the spring runs is intense

How people can help

What individuals can do

  • Conserve water — Edwards Aquifer pumping directly determines spring flow
  • Stay on designated paths and out of vegetation beds when tubing or swimming in the San Marcos and Comal rivers
  • Never release aquarium plants or animals into spring-fed waters

What communities can do

  • Support Edwards Aquifer Habitat Conservation Plan implementation and drought-stage water restrictions

Educational actions

  • Visit the Meadows Center at Spring Lake to see the spring ecosystem directly

Habitat support

  • Volunteer for native aquatic vegetation planting and invasive removal in the spring runs

Organizations and programs to learn about

  • Edwards Aquifer Authority
  • USFWS San Marcos Aquatic Resources Center
  • The Meadows Center for Water and the Environment

Educational notes

  • A species whose survival is decided by municipal water policy, not by hunting or habitat clearing.
  • Illustrates that local abundance and extinction risk are not the same thing.

Sources and references