Having your own pond full of fish can bring lots of enjoyment. Here are the answers to some of the most commonly asked questions about managing fish ponds.

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Will fish stocked into my pond survive?

It is important to know the lowest oxygen levels that occur in your pond during the year.  This worst case scenario usually occurs in August.


In small, shallow ponds of less than an acre, the ponds’ water supply is the most reliable source of oxygen.  If you have a pond that does not discharge water in August and starts getting shallower, it is also probably low in oxygen and risky to stock with fish.

What kind of fish should I put into my pond?

  • If a pond rarely exceeds 59 F, brook trout are a good choice.
  • If the pond rarely exceeds 69 F, rainbow trout will generally do well.  
  • If a pond stays in the 70s, only warm-water fish will survive, but these species are illegal to stock in Vermont. 

When measuring the pond’s water warmest temperature, choose a hot August day.  Tie a thermometer onto the end of a fishing line, place a bobber six feet above it, and cast it out to the center of the pond.  The goal is to test the deeper parts of the water.  After a couple of minutes, quickly reel the thermometer in and read the temperature.  

Where can I get fish to put into my pond?

Only trout are legal to stock in Vermont. If fish are to be purchased out of state, then an importation permit is required, which can be obtained from the department.


Get list of approved trout sources

How many fish should I put into the pond?

The following are some conservative stocking rates:

  • If adult fish are already in the pond, it is recommended to stock the pond with adult fish. Stocking 60 to 200 trout of 7- 10 inches per acre should be adequate.
  • If the pond contains no other fish, stocking spring fingerling trout of 2-3 inches is less expensive, and may be stocked at 200 to 400 trout per acre.
  • As a compromise stock fall fingerlings at 150 to 300 per acre, which are better at avoiding predation than spring fingerlings, but are more likely to die over the winter than adults.

If you are not sure if conditions are favorable for stocking trout, stock a few and see if it works.

Will stocked fish reproduce in my pond?

Trout rarely reproduce in a pond, allowing the pond owner to control of the number and size of fish in the pond. Warm water fish generally reproduce, usually leading to large numbers of small, stunted fish that are not generally suited for fishing or eating, and sometimes even impact swimming.

Why did my fish die?

Here are some of the most common reasons that stocked fish die:


Problems in transport

Fish dying immediately after stocking may have been severely stressed during transport and introduction.  The pond’s water temperature should not be greater than 10 degrees more than the water in the distribution unit at stocking.  For rainbow trout, the pH of the pond water should not be significantly less than the water the fish have been reared in.


Oxygen deprivation

The most frequent and devastating fish die-offs occur after several cloudy days with little wind, which results in too little oxygen in the water.  If you see fish that appear to be gulping air at the surface, try to get more water to the pond or adding some sort of aeration.


Pumping water from the bottom of the pond or spraying water across the surface will help aerate the water.  Low oxygen levels can also occur in the winter under the ice, particularly if too much snow covers the ice.


Disease

If fish start dying within a few days of being stocked and the number of dead fish keeps increasing daily, it is possible the fish were diseased and the disease is killing them.  Contact the hatchery that reared the fish for more information.


Predators

If there are constantly a few dead fish over a period of time, it is possible that predators such as herons, ducks, or mink are killing fish.  Look for tracks and other signs of these species along the shore.  There also are some natural parasites that can exist in fish ponds that can mimic the continuous, gradual die-off caused by predators.

How can I stop predators from eating my fish?

Herons, ducks, kingfishers, mink, and otters will eat fish.  A nonlethal and inexpensive method to avoid depredation is to string two strands of monofilament fishing line around the perimeter of the pond, at roughly 12 inches and 18 inches above the ground. This will stop many wading birds and ducks from entering the pond.


This can also be accomplished with a single strand of electric fence such as the type used to fence cattle. By adjusting the height of electric fence, it can be effective for wading birds and ducks, as well as mink and otter.

How can I get fish out of my pond?

Fish can sometimes overpopulate the pond, become stunted in size and a nuisance. Draining the pond, leaving the fish high and dry is one method. However, care must be taken to avoid illegally allowing the fish to escape during the drawdown.


Another method is to seine, or net the fish from the pond and dispose of them. Many minnow dealers have seines that can cover ponds a half acre or less, but this generally has to be repeated every few years as not all fish are scooped up.

Where can I get more information about pond management?