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Aquaculture / Fisheries - "Center of Excellence"

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Fish Kill page header

Fish kills can be heartbreaking and financially costly experiences that are bound to happen to some extent in most ponds eventually. The severity and frequency of fish kills can be reduced by proper management and precautions, but they can’t always be avoided. 

If you are experiencing a fish kill, or think you might be experiencing one, follow the instructions below to determine what caused it, what if anything can be done to stop it, and how to prevent them from happening again in the future. The first step is gathering information so that you can explain in detail the background of your pond and what is currently happening to it to a fishery professional. The more information you can provide, the more likely the source and cause of the problem can be accurately diagnosed. 

Necessary Information

  • Your name?
  • Phone number?
  • Email?
  • Address/location of the pond so the fishery professional can locate it on satellite images and/or make a site visit for sampling?
  • What is the pond used for?
  • What is the land that surrounds the pond used for? (Example: pasture, wooded bottomland, crop fields, urban streets and parking lots, etc)
  • How old is the pond?
  • What is the maximum water depth?
  • If there are aquatic plants growing in the pond, what species are they and how much of the pond area is growing them? (if plant species is unknown, take the best digital picture of the plant you can so it can be emailed to the fishery professional)
  • Have you applied any herbicides to the pond or to vegetation near the pond recently?
  • Have you fertilized the pond, if so how much?
  • Have you fed the fish, if so how much?
  • Have you added water to the pond from a well recently?
  • Have you stocked new fish recently?
  • Have you installed new habitat to the pond recently?
  • Have you installed a new aerator or started up an aerator for the first time recently?
  • What was the weather like at the pond a few days before the fish kill? (Air temperature, wind speed, cloud cover and precipitation a few days ahead of the kill are important factors)
  • Shortly before the fish kill, did the pond change colors or begin smelling differently? 
  • How many and what species of fish have been stocked into this pond?
  • When where the fish first observed acting differently, or dying?
  • What species of fish are dead? (if unknown, take the best digital picture of the fish you can so it can be emailed to the fishery professional)
  • How many fish of each species are sick or dead?
  • How large are the fish that are sick or dead?
  • Did the fish become sick or die all at once or have a few been dying each day for several days?
  • Do any of the fish have lesions, open sores, frayed fins or other abnormal characteristics?
  • If there are any surviving fish swimming near the water surface, how are these fish behaving and do they have any obvious lesions?

Who to Call

When you have collected the necessary information, the next step is to contact a fishery professional. The geographic location of the fish kill, whether it occurred in public or private waters, and the suspected causative agent can determine which entity is most appropriate to contact. 

If the fish kill occurred in public waters, contact the Arkansas Game and Fish Commission: 
www.agfc.com
(800) 364-4263 
AGFC logo
If agricultural pesticides are suspected as a potential cause of the fish kill, contact the Arkansas Plant Board: 
www.aad.arkansas.gov/arkansas-state-plant-board
(501) 225-1598
AR Plant Board logo
If other pollutants or toxins are suspected as a potential cause of the fish kill, contact the Arkansas Department for Environmental Quality: 
www.adeq.state.ar.us
(501) 682-0744 / (501) 682-0923
ADEQ logo
If the fish kill occurred in private waters, contact the nearest UAPB fish health diagnostic facility:
 

Jonesboro
(870) 540-7805

Lonoke
(501) 676-3124 / (773) 383-9037

Pine Bluff
(870) 575-8137 / (773) 383-9037

Lake Village
(870) 265-5440 / (870) 737-3281
 AQFI logo












Samples

It is not always necessary to take samples to determine the cause of fish kills in ponds. The vast majority of fish kills in ponds are due to oxygen depletion. The cause of oxygen depletions can vary, but fishery professionals can usually accurately diagnose the cause based on answers to the questions above. If samples are needed, a representative from the entities mentioned above can sometimes collect them via site visits. Site visits are not always logistically practical or there may not be staff available to visit at that time. In those cases, ask the fishery professional you contact what samples to collect and how to collect and deliver them.

What to do Next

There is very little that can be done to stop a fish kill from progressing once it has begun. If you have an aerator installed, running it continuously can save some fish if the fish kill is caused by oxygen depletion. Adding well water to a pond may not help because groundwater is often low in dissolved oxygen. Well water can be oxygenated by splashing it against a solid surface or allowing it to tumble through perforated surfaces before entering the pond. Approved antibiotics and chemical water treatments are sometimes used during fish kills on commercial fish farms but these practices are almost always impractical in private ponds. The treatments can cost more than restocking the pond and most if not all of the fish would already be gone by the time the treatments could be purchased and applied in most cases. 

Following a fish kill, the fish population should be assessed to determine what is left. The easiest way to accomplish this is to hire a pond management company to conduct an electrofishing sample. The next option is to use rod/reel fishing and seine net sampling to assess the fishery yourself as described in fishery assessment and management. The third option would be to drain the pond completely, kill or remove all remaining fish and restock from scratch. If the fish kill was minor and affected all species of fish in the pond similarly, restocking may not be necessary; natural reproduction can replenish fish populations quickly. If a single species was hit harder than others, it may be necessary to restock that species to help restore population balances, but this is not an exact science. If the fish kill was substantial and all species were hit hard, a complete pond renovation and restock from scratch is often the strategy most likely to produce satisfying results in the shortest amount of time. 

How to Prevent Fish Kills

The best defense against fish kills is simply following sound pond management practices. If there was a single act that would decrease your chance of experiencing a fish kill more than any other, it would be installing and regularly operating an aeration / circulation system. General practices that will help reduce the likelihood of fish kills include:
  • Build the pond so that water depth does not exceed about 12 feet
  • Prevent livestock from entering pond if possible
  • Install and regularly operate an aerator
  • Do not over-stock
  • Do not over-fertilize
  • Do not over-feed
  • Prevent overgrowth of vegetation and use herbicides properly
Additional resources:
SRAC 0472: Investigating a Fish Die-Off and Submitting a Sample for Toxicology or Disease Diagnosis
SRAC 4605: Algal Toxins in Pond Aquaculture

What to read next:
Fishery Assessment and Management
Starting Over
Stocking Rates