Like any ecosystem, the San Marcos River is happier without invasive species taking over. This spring-fed river in San Marcos, Texas, maintains its 72-degree temperature year-round, making it popular with humans, fish and turtles who live in the area. But a problem arises when humans decide they no longer want their exotic aquarium fish and decide to release these non-native species into the river. Fortunately, the San Marcos Parks and Recreation Department has devised an innovative way to protect both the river and the unwanted fish.

fish tank with sign that reads "Pet Fish Drop Off Location"

Inhabitat spoke with Melani Howard and Eric Weeks to learn more about San Marcos’ Pet Fish Drop Off program. Howard is the Habitat Conservation Plan Manager for San Marcos’ Engineering and Capital Improvements Department. Weeks is the coordinator of the Discovery Center, an interpretive center for the Blanco and San Marcos rivers, parks and associated trails.

Related: Robotic fish offer a solution to controlling invasive species

Inhabitat: How and when did the program start, and why was it needed?

Howard and Weeks: The program started in 2017 to reduce the number of non-native fish being dumped into the San Marcos River from aquaria and, most importantly, to educate the public about the impacts of non-native fish on native populations. We started with a small outside pond, but the predators eventually turned it into a “food bowl,” so we had to move the program to our inside tanks.  We have three large aquaria — one is dedicated to native species and the other two we use for the Fish Drop Off program.

two fish swimming in a pond

Inhabitat: How many fish do you usually have at once?

Howard and Weeks: We typically have anywhere between 15 to 30 fish total in both aquaria.

Inhabitat: What types of fish have people dropped off?

Howard and Weeks: Suckermouth catfish (our target fish to collect, as it is incredibly invasive), goldfish, angelfish, neons, beta, zebra, bala, gourami, cichlid, rainbow, Oscar, aquatic frog, carp, tetra and platy.

Inhabitat: Do the fish get “adopted” and brought home to new aquariums? If so, how does that process work?

Howard and Weeks: Yes, all the fish are adoptable by anyone who wants them. The adoption process has been fairly constant, although has slowed down somewhat because of decreased marketing. Individuals just have to stop by the Discovery Center, Monday to Friday 8 a.m. – 5 p.m., with their own take-home containers.

Inhabitat: Who takes care of the fish, and what kind of care is provided?

Howard and Weeks: Discovery Center staff cares for the fish. Care consists of regular cleaning, water changes and feeding.

fish and plants in a pond

Inhabitat: What results have you seen from this program?

Howard and Weeks: The program has been used by college students primarily, but we have also received goldfish after the carnival has been in town (ugh), and people are very grateful to have such a program. Adopters are also quite pleased to be getting free fish. But the most important result is public education regarding the impacts of aquaria dumping. 

Inhabitat: What has the public response been?

Howard and Weeks: Incredibly positive. It’s been fun.

Inhabitat: Could you give us a brief overview of your involvement with the fish program, as well as your other duties as watershed protection manager?

Howard and Weeks: My involvement consists of responding to questions and assisting the public with dropping off or adopting the pet fish, tracking the number of fish and species type dropped off/adopted for reports and ensuring proper care and feeding. We also have education and outreach with the intent to reduce the introduction of non-native fish species in the San Marcos River.

Watershed protection manager duties include implementation of the Edwards Aquifer Habitat Conservation Plan to conserve habitat for endangered and threatened species that inhabit the upper San Marcos River. Conservation measures include non-native predator fish removal, non-native aquatic and terrestrial vegetation removal, aquatic and terrestrial native plantings, recreation management, litter removal, bank stabilization, education and outreach and water quality best management practices.

white fish in a fish tank

Inhabitat: What are the main threats to the San Marcos River?

Howard and Weeks: The primary threat is overpumping of the Edwards Aquifer, which feeds the San Marcos River, water quality impacts from urbanization, impacts of recreation, invasive species — all these threaten the diverse, high quality habitat in the river, which supports diverse natives including several endangered species.

+ Pet Fish Drop Off Program

Images via Melani Howard