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Fish Health
Program Description

The main emphasis of Vermont's Fish Health Program is the prevention and management of serious fish diseases. The program is responsible for the development and implementation of programs designed to help protect wild fish populations and fish culture station fish stocks. Key responsibilities of the program include:
  • Conducting annual fish health inspections on all state owned and private fish culture stations and investigating specific diseases when they occur on facilities.
  • Developing statutes and regulations designed for the prevention and management of serious fish diseases.
  • Administering Vermont's fish importation and fish propagation permit programs.
  • Investigating fish kills and studying fish disease agents in the natural environment.
  • Providing technical assistance in fish heath related matters to related programs and members of the public.
  • Participating in New England's fish health technical committee entitled "New England Salmonid Health Committee".
Fish Health Laboratory - Location

The department has a fish health laboratory that is equipped to diagnosis many parasitic, bacterial and viral fish pathogens. The laboratory is not open to the public.

Most Commonly Asked Questions About Fish Health In Vermont

Question 1.) What are the tiny black, yellow or white grubs in the fish that I catch? Are these fish safe to eat?

Answer: These are small parasites that are termed "Digenetic Trematodes". Commonly known as "Black spot, Yellow grub and White grub, they are very common in many fish species in Vermont waters and worldwide. The parasites have a complex life cycle that involves fish, water dwelling birds, and other invertebrates such as snails. They are not known to infect humans and their overall damage to fish populations are negligible.

There is no known cure for the parasite in natural waters.

Question 2.) Why are the trout dying in my small, private pond?

Answer: In many situations, it can be difficult to document the exact cause of individual fish deaths in small ponds. The two most common reasons are:
  • Summer related fish kills - This type of fish kill often occurs in very small, shallow ponds that heat up due to extreme water temperatures. Warm water hold's very little oxygen and trout will suffocate. If a pond rarely exceeds, 69 degrees Fahrenheit, Rainbow trout should do well. Brook trout should do well in colder water temperatures below 60 degrees.
  • Note: Brook, Brown, and Rainbow trout are the only fish species that can be stocked without a permit. Contact the Vermont Fish & Wildlife Department for a list of approved in-state and out-of-state sources of trout.
  • Winter related fish kills - This condition is often noticed shortly after ice-out. Low oxygen levels can occur in the winter under the ice, particularly if there is a thick ice and snow cover. Winterkill is most common in highly vegetated, nutrient rich ponds.

Question 3.) What caused the fish kill in a particular body of water in Vermont?

Answer: The Vermont Fish & Wildlife Department annually documents fish kills, most of them related to natural causes. They can be classified as three basic types:) Winter Kill, Spring Kill, and Summer Kill. All of these types of events can have low oxygen levels associated but with spring and summer kills fish death is usually related to a combination of stressful factors that overwhelm the fish's immune system. These factors include: rapidly fluctuating water temperatures, extremely warm water temperatures, strenuous spawning activity, unbalanced fish populations, poor nutrition and fish diseases.

Note: Occasionally, we document fish kills related to the illegal dumping of toxic chemicals. Please report fish kills and any abnormal fish condition to the Vermont Fish & Wildlife Department.

Fish Health Fact Sheets
Useful links:

State of Maine -

U.S. Fish & Wildlife Service, Wild Fish Health Survey -

Focus on Fish Health page -


Copyright © 2003-2015 Vermont Fish & Wildlife Department. All Rights Reserved.