New Research Identifies Impacts to Developing Zebrafish Exposed to Contaminants

Using genetic sequencing, a team of scientists investigated impacts to molecular pathways responsible for impaired sensory systems in zebrafish (Danio rerio). These findings aid in the understanding of how environmental contaminants negatively affect organisms.

A magnified photograph of four zebrafish embryos, upright in a row against a purple gray background.
Zebrafish are a freshwater fish commonly used to study diseases and contaminant effects in humans and other organisms. Image credit: University of North Texas.

MARCH 12, 2026 — In 2026, the University of California, Riverside; University of North Texas, NOAA’s Office of Response and Restoration Assessment and Restoration Division, and partners, published a follow-up to a 2025 study examining how developing zebrafish are impacted by exposure to Aroclor 1254, a mixture of industrial chemicals, known as polychlorinated biphenyls (PCBs), which can harm living organisms in multiple ways. The initial 2025 research linked exposure to Aroclor 1254 to impaired neurological and heart rate in early life stage zebrafish. The newer publication, titled "Aroclor 1254 impairs visual and neurosensory signaling pathways independent of the aryl hydrocarbon receptor in larval zebrafish," reports results that lead to a better understanding of how PCBs interact with biological processes.

Zebrafish are commonly used in laboratory studies because they help scientists understand how contaminants affect fish and, in some cases, human health. Chemicals like PCBs are known as “legacy contaminants” because they persist in the environment for decades. They build up in the food chain, moving from small organisms to fish and wildlife, and to consumers of contaminated food. These pollutants can interfere with growth, development, reproduction, and survival, and cause cancer.

Using a technique called RNA sequencing, the team examined which genes were turned on or off in exposed early life stage zebrafish to understand how Aroclor 1254 causes harm. Bioassays were also conducted to assess the toxicity of Aroclor 1254 to larvae exposed as embryos. Findings of this study include:

Eye tremor behavior of seven days post fertilization larval zebrafish. Video credit: University of North Texas.
  • Information about how this chemical mixture impairs pathways involved in vision and nervous system development.
  • Eye diameter decreased and eye tremor and tremor response behavior increased.
  • The resulting visual impairment in PCB-exposed fish may reduce the ability of young fish to survive in the wild.

These research findings underscore the importance of understanding how legacy contaminants like PCBs continue to affect aquatic life at critical stages of fish development as scientists work to protect and restore ecosystems impacted by hazardous waste and oil spills.

The full research dataset is forthcoming and will be published for public access on the National Centers for Environmental Information website. Meanwhile, the sequencing data is available now at The National Center for Biotechnology, and the bioassay data will follow soon.

Last updated Wednesday, March 18, 2026 7:38am PDT