SAN ANTONIO – Aquarium fish are considered an invasive species and do not belong in the San Antonio River.
A public service announcement from the San Antonio River Authority (SARA) details the risks to the ecosystem when people dump fish into local waterways.
Some of the invasive species causing the most harm to the San Antonio River are vermiculated sailfin catfish and plecostomus, both referred to as armored catfish, and tilapia.
Armored catfish burrow into riverbanks, which leads to erosion of the banks and eventually bank collapse, according to a blog post from SARA.
“This leads to unstable sections of creeks and rivers and increased turbidity,” SARA Environmental Sciences Manager Shaun Donovan told KSAT.
Turbidity refers to the murkiness of the water, which actually increases the temperature of the water while simultaneously decreasing oxygen levels that are needed to sustain native fish, freshwater mussels, and aquatic insects.
Donovan also said non-native tilapia can out-compete some of the native species for habitat and referred to them as “a very aggressive species.”
“These invasives are significantly more common in disturbed parts of the river such as the downtown Riverwalk,” Donovan said.
According to SARA officials, aquarium hobbyists will purchase non-native species from pet stores for their home aquariums and then release them into local creeks and the San Antonio River when the fish outgrow their tanks.
“While they may be well-intentioned, these citizens are unknowingly wreaking havoc on the San Antonio River ecosystem,” SARA officials said.
Returning fish to pet stores or trying to rehome them are the two options pet owners should consider, according to SARA.
George Rodríguez is the co-owner of Papa Jim’s Tropical Fish on the city’s South Side. His team works to educate clients on the commitment required ahead of any purchase.
“The main thing is when you purchase an aquatic fish, make sure we have the the aquarium big enough to support the fish when it gets to its full size,” Rodríguez said. “Most of the time you would need at least like a 75-gallon or bigger (tank aquarium for species like the armored catfish), because it can get upwards of about a foot and a half to two feet. And they are very disruptive when they swim.”
Papa Jim’s Tropical Fish is aware of the risk invasive species pose to the river and open to the community surrendering their aquatic pet at their location.
“A lot of times (local pet stores) will take the fish in, keep them and then find bigger aquariums,” Rodríguez said. If you call us, we’ll be more than happy to help you. We have some 300-gallon aquariums in the back.”
Removing the fish from the river isn’t possible. Donovan said SARA is dealing with the issue from a mitigation perspective rather than to eliminate or restore the system to what it once was.
Removing the fish from the river isn’t an option either.
“We do not conduct a targeted effort to remove invasive fish species from the river,” said Donovan. “The invasive species most commonly found, tilapia and armored catfish, are abundant enough that a targeted effort would not have a meaningful impact on their populations. The most intensive efforts we conduct for non-native removal is during de-watering events.”
The next scheduled dewatering of the San Antonio River is expected to take place in the downtown stretch in January 2022.
You can report any sightings of invasive species in the San Antonio River by calling (866) 345-7272 or contacting SARA via the River Authority’s website.
Anyone wanting to be involved in future efforts to mitigate the impact of non-native species in local creeks and the San Antonio River can sign up to join the River Warriors.
If you need to surrender your aquatic pet, call Papa Jims Tropical Fish at 210-927-7991.