Tag Archives: fish health

Scientists net virus behind tilapia die-offs in Israel and Ecuador

An international scientific team led by researchers at Columbia University’s Mailman School of Public Health and Tel Aviv University has identified and characterized a novel virus behind massive die-offs of farmed tilapia in Israel and Ecuador, which threatens the $7.5 billion global tilapia industry. A paper in the journal mBio describes tilapia lake virus (TiLV) and provides information needed to fight the outbreak.

Known in its native Middle East as St. Peter’s fish and thought to be the biblical fish that fed multitudes, tilapia provides inexpensive dietary protein. The world’s second most farmed fish, tilapia is also the basis of aquaculture employment in developing countries in Asia, Latin America, and the Middle East. (The United States is the leading tilapia importer globally.) Since 2009, Israel has seen precipitous declines in tilapia, with annual yields plummeting as much as 85 percent–highly unusual considering the fish is known to be relatively resistant to viral infections. Similar die-offs have been seen in Ecuador and Colombia.

Diseased tilapia

Tilapia diseased from tilapia lake virus infection, Ecuador. Photo: Hugh Ferguson.

The scientists used high-throughput sequencing to determine the genetic code of the virus from tissue taken from diseased fish in Israel and Ecuador. This process would normally be sufficient to identify the culprit, but in this case, the resulting DNA sequences didn’t match any known virus, with the exception of a small genetic segment, that only remotely resembled a virus associated with the reproduction of influenza C.

Undeterred, the researchers employed other tools from their scientific tackle box, providing ample evidence that the genetic material was the same as the implicated virus dubbed TiLV. They used mass spectroscopy to characterize the proteins in cells growing the virus, which matched those they expected to see based on the genetic sequence. By analyzing the structure of viral DNA, they went on to observe 10 gene clusters with complementary endpoints, suggesting a circular form associated with a common type of viral reproduction involving a protein called a polymerase.

Finally and conclusively, healthy fish were exposed to TiLV cultured in a laboratory, resulting in disease that matched with what was seen in those countries: in Israel, the fish had swollen brains; in Ecuador, liver disease. In the coming weeks, the researchers will publish on the link between the TiLV and an outbreak of disease among tilapia in Colombia.

“The TiLV sequence has only minimal similarity in a small region of its genome to other viruses; thus, the methods we typically use to identify and characterize viruses through sequencing alone were insufficient,” says first author Eran Bacharach, a molecular virologist at Tel Aviv University.

“It appears to be most closely related to a family of influenza viruses called orthomyxoviruses; however, we still don’t understand much about its biology,” adds Nischay Mishra, associate research scientist at the Center for Infection and Immunity at Columbia’s Mailman School.

Importantly, the findings provide the genomic and protein sequences necessary for TiLV detection, containment, and vaccine development.

“We are shifting our focus now to implementing diagnostic tests for containment of infection and to developing vaccines to prevent disease,” says Avi Eldar of the Kimron Veterinary Institute in Bet Dagan, Israel.

The team of 18 researchers represent five institutions in four countries: the Center for Infection and Immunity and the New York Genome Center in the U.S., Tel Aviv University and Kimron Veterinary Institute in Israel; the University of Edinburgh, Scotland; and St. George’s University, Grenada, West Indies.

“The New York Genome Center was excited to join in characterizing this novel virus and contribute to this important environmental and globally impactful research,” says Toby Bloom, the Center’s deputy scientific director.

“Gumshoe epidemiology, molecular gymnastics and classical microbiological methods were required to link this new virus to disease,” says Ian Lipkin, senior author, director of the Center for Infection and Immunity and John Snow Professor of Epidemiology at the Mailman School. “Resolution of this mystery was only possible through the concerted efforts of this talented group of international collaborators.”

While best known for identifying viruses behind human disease, the Center for Infection and Immunity, pinpointed the virus beyond a disease that decimated salmon farms in Europe in 2010. They have done similar work with seals, sea lions, and Great Apes.

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The current research was supported by grants from the United States-Israel Bi-National Agricultural Research & Development Fund (BARD IS-4583-13), the Israel Ministry of Agriculture & Rural Development Chief Scientist Office (847-0389-14), U.S. National Institutes for Health (AI109761), USAID PREDICT, and a fellowship to J.E.K.T. from the Manna Center Program in Food Safety and Security at Tel Aviv University. The authors declare no conflicts.

Aquaculture Symposium to Focus on Infectious Diseases of Tilapia & Strip Catfish

Aquaculture Symposium taking place on 24 of March all day at Meeting Room 2 (3rd floor) of SECC in Ho Chi Minh City Vietnam which focus on Infectious diseases of Tilapia & Strip catfish invite 4 Fisheries experts from Veterinary Pathobiology, Faculty of Veterinary Science, Chulalongkorn University Bangkok, Thailand and the specialist in Tilapia from Vietnam to join the session.

The interesting topics are Franciscellosis, Streptococcosis, Columnaris disease in Tilapia and Strip catfish and Concurrent infection & Miscellaneous diseases, Antibiotic resistance in Aquaculture, Vaccine for Tilapia and Strip catfish and close session with Viral Nervous necrosis in Tilapia. This class is special for fish farmer to understand and study how to solve the infectious diseases of Tilapia and strip catfish in Vietnam. FAVA believe that this class will create the valuable knowledge for all delegate and the 120 seats are limited.

All conference program, please visit here

For more information of ILDEX Vietnam 2016, please visit www.ILDEX-VIETNAM.com

Aquaponics Workshop Offered at University of the Virgin Islands

University of the Virgin Islands, Albert A. Sheen Campus
St. Croix, USVI

Program – 3-day course that will provide in-depth knowledge of the principles and practical application of the aquaponic system that has been developed at the University of the Virgin Islands. Participants will be introduced to the system design that maintains water quality by hydroponic plant culture (aquaponics), Fish production instruction will be conducted using both the Nile tilapia (Oreochromis niloticus) and red tilapia. Hydroponic plant production will focus on vegetables, culinary herbs and ornamental flowers.

Instruction – Each day will include a half-day of classroom lecture and a half-day of hands-on field work. Participants will learn the technology through presentation of the theory and practical skill development. Each student will be given a USB Flash Drive of reference materials and course content. Water quality labs will cover the methods of analysis and the use of water quality test kits. Field work will include fish handling, vegetable production and system operation.

Fee – Registration is required.  The course fee is $600.  Your registration will be confirmed by email upon receipt of payment.  The number of participants is limited and early registration is recommended.  The course fee does not include transportation to St. Croix, lodging, meals or local transportation.

Facilities – UVI is located in the heart of beautiful St. Croix. The Aquaculture Program operates fifteen research-scale systems (six aquaponic and nine biofloc) as well as commercial-scale aquaponic and biofloc systems, a fry sex-reversal system, a recirculating system for fingerling rearing and a purge system. The program annually produces about 20,000 lbs. of tilapia and a variety of vegetables.

Topics

Aquaponic system Plant production
   System design and management    Seedling production
   Components    Disease and insect control
   Construction techniques    Harvesting and packaging
Operation Economics
   Water quality    Capital budgeting
   Fish production    Operations plan
   Stocking rates    Marketing
   Feeding, growth and survival Fingerling production
   Harvesting and processing    Brood stock management
   Breeding/Fry sex reversal

Upcoming Workshop Dates:

  • February 27 – March 1, 2013
  • April 3 – 5, 2013
  • May 8 – 10, 2013

For the latest information, see Registration Announcement.

Aquaculture: Cage Culture

A new type of farming in Indiana is gaining in popularity. This farming uses water rather than water. Aquaculture, or fish farming, is the practice of raising or harvesting fish (or other aquatic life) in a controlled environment.

There are four culture systems where you can raise fish:

  • Ponds
  • Raceways
  • Recycling Systems
  • Cages

Cage culture is a popular form of aquaculture that has many advantages that include resource flexibility, low cost, and simplified harvesting. This article focuses on cage culture.

Before investing any capital in a new business venture, it’s always good practice to do a thorough market analysis and develop a business plan. This will help you determine the size of the market, competition, and capital requirements. Markets are scalable from home consumption, to retail, to wholesale distribution.

Site Selection

After determining aquaculture farming is a viable interest for you to pursue, then the next step is to locate a body of water that will meet the biological and ecological requirements of cage culture. Lakes and quarries are possible sites. Some requirements to consider:

  • Size of body of water – at least 1/2 acre, but preferably an acre of larger
  • Water depth – at least 6 feet deep
  • Water quality – determine pollution sources and surrounding topology
  • Access to electricity – for aeration or other needs
  • Access to site – by boat or vehicle

Species Selection

Consider the marketability of your product and your grow out site. In Indiana, tilapia is a popular fish because of its large size, rapid growth, and hardiness. Hybrid striped bass, catfish, rainbow trout, and largemouth bass are other candidates for cage culture.

Hatcheries / Fingerlings

Once you have selected your species (or species), you need to find a hatchery that can reliably provide high quality fingerlings at a fair price.

For a list of commercial suppliers, see the Indiana Dept. of Natural Resources website:

Cages

Cage size determined the number of fingerlings to purchase. You want 5 to 7 fingerlings per cubic foot. Cages come in all size, but the minimum depth should be 4 feet. Cages can be purchased or homemade. Cages range in cost from $150 to $500 per cage. The size of your fingerling will determine the mesh size you need.

Make sure you leave at least 10 feet between cages when you add them to your site. Cages must be in quiet areas (away from swimmers) and easily accessible.

Water Quality

The water for your cage system must contain adequate oxygen to support the fish you are growing. Natural water oxygen can be supplemented with aeration. The dissolved oxygen level and temperature of the site should be monitored closely.

Fish Handling

Fish are shy animals and are easily subject to stress. You need to avoid stressing your fish to optimize their growth. Transport your fingerlings in a well oxygenated container.

Feeding

Fish grown in cages rarely obtain enough natural food and are therefore dependent on feeds supplied by the farmers. Floating feed is the preferred feed type and hand feeding is best. Feeding the fish with the proper amount is key for optimal growth, water quality maintenance, and operational expenses.

Fish Health / Husbandry

Vigilant observation and proper fish handling techniques to reduce stress, help maintain culture conditions. Biofouling is a potential problem that can be prevented by proper maintenance. Diseases may occur from time to time. Evidence of fish disease includes skin discoloration, open wounds and lesion, fin erosions, spots, and
erratic behaviour. Seek a disease diagnosis from an accredited lab and follow the recommended prevention methods.

Harvesting

Fish should be harvested as soon as they reach marketable size. Make sure you minimize stress during harvesting and maintain fish in well aerated transport.

References:

Continue your education by seeking out additional literature and by consulting with extension agents and other aquafarmers