Silk Microneedles Vaccinate Fish Underwater
Fish farmers could vaccinate much smaller stock without sedating it or handling each animal with metal needles.
Updated on Nov. 6, 2026 in Pet Health
MIT and USDA researchers developed food-grade silk microneedles coated in shellac that stay attached to fish skin underwater and can deliver bacterial and DNA vaccines. The device was tested in rainbow trout and could vaccinate fish as small as 1 to 2 grams, which is far below the roughly 30 grams at which current needle vaccination works.
Why it matters
Fish farmers rely on vaccines to prevent disease outbreaks, but today's needle method is labor intensive, costly, stressful for fish, and dangerous for workers, so a gentler underwater option could change how farms protect their stock. The work arrives as farmed aquatic animals have already overtaken wild-caught ones in global food production by weight, and as the population is projected to grow by almost 2 billion people by 2050.
The microneedles were tested in rainbow trout and delivered vaccines underwater to fish weighing 1 to 2 grams, compared with the roughly 30-gram threshold for current needle-based methods. Dry-storage testing over four weeks showed the DNA vaccine structure was half preserved.
The players
MIT
The Massachusetts Institute of Technology, a research university whose engineers developed the silk microneedle vaccine system.
USDA National Center for Cool and Cold Water Aquaculture
The U.S. Department of Agriculture research center that collaborated on the fish vaccine work and supports aquaculture research.
The details
The microneedles are made of food-grade silk coated in shellac, which forms a moisture barrier that keeps them water-resistant until injection. Each microneedle is single-use and designed to pierce wet skin and stay attached while the fish swim. The system can store a range of vaccines, including bacterial and DNA types, and can be tuned to release them over periods from 15 minutes to 24 hours.
Timeline
2021: Farmed aquatic animals first exceeded wild-caught animals in global production by weight.
2022: Li began work on the fish vaccine project in Marelli's lab.
2024: Li received a USDA fellowship funding the project.
November 6, 2026: The article on the microneedle vaccine research was published in ACS Nano.
The Home Front
Farmed fish now outpace wild-caught fish in global production, so disease control on farms carries more weight for seafood supply. A vaccination method that works underwater on small fish would address one of the labor and stress costs that shape how aquaculture scales.
If you keep ornamental or backyard aquarium fish, this research is not yet available for home use and does not change routine care. Keep a record of your fish's health and consult a licensed veterinarian if you notice unusual behavior or illness.
The takeaway
Vaccination tools for farmed fish are moving toward gentler, underwater methods that could reach smaller fish. For household aquarium owners, the practical step is to keep a health log and call a licensed veterinarian when something looks wrong.
Further reading
For more on how animal health care is evolving, see Pet Health.
Source note: This article includes information reported by Ocean News & Technology.
