Using Clay to Fight Fish Disease

Scientists from USDA’s Agricultural Research Service have unearthed a natural material that helps prevent a deadly fish disease. Kaolin, a type of clay found globally, significantly improved the survival of channel catfish with columnaris disease. The disease is caused by a bacterial pathogen, Flavobacterium columnare, which affects the gills, skin and fins of fish, and often leads to death.

Kaolin is a soft white clay that been used for years in cosmetics, medicine, and papermaking. It is also used in manufacturing china, porcelain and other products. Scientists found that adding clay particles to water tanks gave fish a 96 percent chance of surviving the disease, compared to a 76 percent chance when no clay was added to their water.

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ARS Joins Effort to Boost Oyster Production

A scientist from USDA’s Agricultural Research Service in Rhode Island has joined a team of researchers working to restore oysters along the Eastern seaboard. The group is developing new methods to accelerate selective breeding and expand it to new regions along the East Coast. Oyster production has been declining since the 1940s due rising water temperatures, changes in salinity, and Dermo disease.

In addition to being considered a seafood delicacy, oysters are important to the marine environment. As filter feeders, they help improve water quality as they filter their food from the water.

“We are hoping to associate traits like fast growth, disease resistance, and low salinity tolerance with specific regions of the genome,” said Dina Proestou, a research geneticist with ARS’s National Cold Water Marine Aquaculture Center in Kingston, RI. “Once we have that information, we can breed oysters that possess these features in less time and with greater precision.” 

More information can be found at https://tellus.ars.usda.gov/stories/articles/ars-joins-effort-to-boost-oyster-production

Fly Frass Forms Fabulous Fish Food

People gotta eat, and with the world population projected to reach nearly 10 billion in the next few decades, we’ll need to produce a lot more food. Fish farming – aquaculture – is one way of doing that.

ARS researchers have worked with American catfish farmers to develop a feed supplement that not only increases the weight of their fish – meaning there’s more of it to eat – it also helps keep the fish healthier and is environmentally sustainable. The feed, called “frass,” is high in protein and chitin, a compound that helps fish better withstand pathogens by triggering their immune systems.

Frass is the byproduct of farming insects that are non-pathogenic and do not pose a risk for human, animal, or plant health. In this case, black soldier fly larvae are raised on organic waste products until they reach a specific age. Larvae are then processed into protein meal and oil for biofuel. As with raising other “livestock,” larvae leave their own waste – including exoskeletons and residual feed. When processed, frass resembles a crumbly soil and is loaded with nutrients.

More information can be found in our Down on the Farm article.