Releasing Catfish can Destroy Entire Ecosystem

Releasing pet catfish in the wild can lead to the destruction of an entire ecosystem. A new study from researchers at Cornell University has found how these fish deplete essential nutrients in the ecosystem, killing native marine organisms.

In the United States, Blue and flathead catfish are considered an invasive species, especially in the Chesapeake Bay where they are growing at a rapid rate. The current study was conducted on sailfin catfishes that have established themselves in non-native waters after aquarium owners released them in the wild. In many countries, rise of the sailfin catfish population has been associated with decrease in native fish population.

The fish belong to the Loricariidae family and are known as "plecos" or "algae eaters". They eat up vast quantities of algae and sequester essential phosphorous in their bodies. The low levels of phosphorous lead to an altered nutrient cycle, which in turn results in many organisms unable to survive in the region.

The present study was conducted in a river in Mexico. Researchers looked at the changes in nitrogen-phosphorous levels before and after the arrival of the invasive species. The study showed that catfish released by aquariums can drastically change an ecosystem.

"By examining the body chemistry of plecos and the chemistry of the system they are invading, we found that these fish have the ability to fundamentally change how the system works," said Krista Capps, postdoctoral research fellow at the Maine Sustainability Solutions Initiative and lead author of the study

Responsible pet-keeping doesn't just involve taking care of the beloved pet, but also knowing that exotic pets should never be released in the wild. There are many cases where people have introduced a species into a region, which then led to the destruction of many native species.

The latest study on catfish can serve as a model to predict which species can invade a region, researchers said. Countries such as Australia and New Zealand have laws that prevent people from importing ornamental fish.

"My hope is that this work will stimulate a discussion to think outside the box as to how regulations are made," Capps said.

The study is published in the journal Proceedings of the Royal Society B.