Pond and Lake Topics
Muddy water limits fish production in ponds because the phytoplankton (single-cell plants) at the base of the food chain must have sunlight to grow. Silt and mud deposits also cover fish eggs and fill the pond, and most pond fish feed using their sight.
Controlling the erosion in a pond’s watershed is essential for permanent control of most muddy-water problems. If livestock are muddying your pond, fence off the pond and install drinking troughs below the pond. Some fish species, such as bullheads and common carp, can keep a pond muddy. In this case, renovate the pond and start over.
After you have identified and corrected the source of muddy water, test your pond water for alkalinity. Ponds with low alkalinity also tend to have low hardness and variable pH, which can cause clay particles to remain in suspension for long periods of time. If alkalinity is less than 50 ppm, adding agricultural limestone may help clear the pond. Spread 2 tons of crushed agricultural limestone per surface acre following the recommendations presented in the Water Quality section. The limestone dissolves and releases calcium and magnesium ions that settle the clay over several weeks. Once the pond is cleared, the small algae begin to grow, and muddy water conditions are unlikely to redevelop.
If alkalinity is above 50 ppm or if adding agricultural limestone does not clear the pond, one of the following methods may help remove the clay from the water:
- 500 pounds of organic material per surface acre, such as old hay (approximately 10 square bales per acre broken up and broadcast evenly over the pond surface), cotton seed husks, compost, or other similar organic material. Be careful using organic material in the summer, since decomposition may deplete oxygen and cause fish to die.
- Apply 40 to 90 pounds of alum (aluminum sulfate) per acre-foot of water. The dosage depends on the severity of the muddy water. Treat moderately turbid water (can see about 12 inches in the water) at 40 pounds per acre-foot, but severely turbid water (can see less than 6 inches into the water) may require up to 90 pounds per acre-foot. This translates to about 200 to 450 pounds of alum per surface acre of water for a pond with 5-foot average depth. Alum removes alkalinity from ponds, lowers pH, and can lead to fish kills in ponds with low alkalinity. To counteract this, apply hydrated lime at the same time as alum at half of the alum rate. Hydrated lime by itself can cause fish kills, so be careful when using this method to clear ponds.
- Use gypsum (calcium sulfate dihydroxide) at the rate of 1,300 to 3,000 pounds per surface acre of water, depending on the severity of the turbidity. Spread the gypsum from a boat over the pond surface, and stir with an outboard motor. The gypsum keeps the water clear as long as the gypsum is not washed from the pond. When used according to recommendations, it does not kill fish, change the pH of the water, or harm livestock. When water clears, you can return to your regular fertilization program.
You do not normally have to feed fish in a healthy bream and bass pond to produce good crops of fish. Natural food organisms are typically abundant enough to feed fish. However, you can increase growth of bream with a supplemental feeding program using a catfish floating feed (about 28 percent protein).
Bluegill readily accept feed and can be attracted quickly to feeding areas. Always feed small ponds stocked at high density with channel catfish or hybrid sunfish to maximize fish growth. Not feeding gives poor results. Here are some points to consider about feeding:
- Feed at the same time and place each day.
- Use floating feed, with a pellet size small enough to be easily eaten.
- Never feed more than the fish will eat in 5 to 10 minutes. Keep in mind that uneaten feed may pollute the water.
- If fish quit eating, stop feeding for a few days. Watch for signs of disease.
- Do not feed in very cold or very hot water.
- Reduce the feeding rate as winter approaches to about one-fourth of the feed rate of the previous summer.
- Automatic feeders give good growth results where small ponds are unattended for long periods.
- Do not try to feed fish up to large sizes without some harvest to reduce the number of fish. Otherwise, crowded large fish may become diseased and die.
Following these simple rules will provide good growth rates while minimizing the risks of deteriorating water quality.
Using Water Level Drawdowns
One of the most useful and inexpensive pond management practices is called a “winter drawdown.” Water levels are reduced in a pond to some predetermined level, generally exposing 35 to 50 percent of the pond-bottom area. Winter drawdowns can be useful in controlling aquatic weeds and can help manipulate fish populations. They are also useful when repairing, redesigning, and liming ponds.
To perform a winter drawdown, make sure the pond has a drain pipe that lets the water levels be lowered and kept down throughout the winter. Ponds without a drainpipe can be retrofitted.
Drawdown for Aquatic Weed Control
Aquatic weed problems are common in farm ponds and usually are challenging to manage. Of the four basic weed control methods (physical, mechanical, biological, and chemical), physical control can be the least expensive and most convenient if it consists of a winter drawdown. Winter drawdown exposes weeds to air-drying and freezing temperatures. This can be an effective weed control technique, especially if done in successive years.
For effective weed control, drop the water level of the pond to expose aquatic weeds in the shallower portions of the pond. Usually, water levels are reduced enough to expose 35 to 50 percent of the pond bottom, but this percentage may vary greatly, depending on topography and design of the pond. Maximum drawdown should be accomplished by mid- to late November, and the water level should remain low through February. Spring rains will refill the pond.
If necessary, deepen the shoreline to 3 feet deep while water levels are reduced. This reduces the likelihood of weeds returning. After reflooding, if weeds persist and begin to sprout, apply an appropriate herbicide. The combination of a winter drawdown, shoreline deepening, and effective early-spring herbicide application usually eliminates or greatly reduces aquatic weed infestations.
Drawdown for Fish Management
Winter drawdown is also a good fish population management technique in largemouth bass/bluegill ponds. By reducing the water level and pond area, you drive forage fish, such as bluegill, out of shallow water refuges and concentrate them in open water, making them more available for bass to eat. This is a good technique to use in ponds having “crowded bluegill” but still containing viable bass populations. The increased feeding by largemouth bass on bluegill reduces bluegill numbers and provides more food for the bass. Routine annual drawdowns can help maintain a balanced bass/bluegill fishery.
Drawdowns can make bass-crowded situations worse. If you have a bass-crowded pond, follow the recommendations to correct the situation, and do not use winter drawdowns until pond balance is restored. Winter drawdown also provides a good opportunity to do repairs on piers, docks, and boat ramps, as well as minor dam repairs and shoreline renovation.
Fish attractors, such as brush tops and gravel beds, can be more easily put in place while the water is down, and this is a good time to deepen edges to the recommended minimum depth of 3 feet. You can use dirt from the shoreline-deepening operation to build earthen piers at various locations around the pond. These piers increase the shoreline area of the pond and provide increased access for fishing.
In most farm ponds, lowering the water level 2 to 4 feet usually exposes the proper percentage of the pond bottom. You must consider the topography of the pond, amount of shallow water, and pond shape and design. Reach the maximum depth of drawdown by late November, and let the water remain down through February. In South Mississippi, the stand pipe can be raised a little earlier, perhaps mid-February, to let the pond refill and not hamper bass spawning activities that begin earlier in that part of the state.
Winter drawdown can be a useful tool if you do it properly. It poses no threat to the fish population and costs nothing if the pond is equipped with a water-control structure. Drawdowns should be done only in the winter—never in summer! The extreme temperatures in Mississippi summers, coupled with the increased activity level of fish and reduced oxygen levels in warm water, will likely result in fish kills in a summer drawdown.
Unexpected Fish Kills
Occasionally, a fish kill occurs in farm ponds because of water quality problems, infectious disease, swarming fire ants (in the spring), or misused agricultural chemicals (pesticides). In some cases, the losses may be enough to affect the balance of the fish population. Get professional help to evaluate the fish population balance after a fish kill. In many cases, a phone call will provide enough information.
Oxygen Depletions and Pond Turnovers
By far the most frequent cause of fish kills in farm ponds is low oxygen. Low oxygen can be the result of two separate phenomena in ponds. The first is simple oxygen depletion, which usually occurs July through September in the time of highest water temperature. Die-offs caused by low dissolved oxygen levels result from natural biological processes, and preventive measures are rarely efficient except for running an expensive aerator every night.
Following are factors that can contribute to low oxygen levels:
- Dense plankton blooms or dense stands of pond weeds.
- Several days of cloudy weather that reduce plant oxygen production.
- High temperatures, which decrease the solubility of oxygen in water and increase oxygen consumption by plants and animals.
- Sudden die-off of plants or algae, especially associated with herbicide use.
- Unusual weather patterns, such as storm fronts and heavy, cold rain.
- Overstocking fish, excessive fertilization, or high feeding rates.
- Input of organic matter, such as hay, straw, or cottonseed meal for turbidity or algae control, and materials such as animal manure or sewage.
Another condition, often called “pond turnover,” can occur after heavy, cold rains in late spring to early fall when temperatures drop suddenly. During calm, hot days, the pond develops temperature layers called “stratification.” The layer of water at the surface is exposed to the sun and warms quickly. This warm layer weighs less than the cool water below, so these layers do not mix. Surface layers contain high levels of oxygen produced by the phytoplankton. The cooler bottom layers are cut off from the surface layers and their sources of oxygen, so oxygen levels drop over time because of normal biological processes. In fact, these deep waters can actually develop an “oxygen demand,” which is like having negative oxygen levels.
When a heavy, cold rain enters the pond, or when there are sustained high winds, it mixes the two layers of water. When this occurs, oxygen levels throughout the pond may drop too low for fish to survive.
A severe mixing event can kill nearly every fish larger than an inch or two in one night. It is not uncommon to find large dead fish on dry land in the watershed above the pond following a turnover. These fish swam up the incoming rain waters seeking oxygen. Adult fish die first, and intermediate-sized fish follow if the oxygen levels are too low or if low oxygen conditions continue for many days.
Usually, by the time you recognize there is an oxygen problem, it is too late to save your fish. But an early symptom of a low-dissolved oxygen level is fish at the surface of the pond at sunrise. Fish appear to be “gasping for air.” If you discover the low oxygen event early enough, you may be able to save some fish by using emergency aeration. A powerhouse-type aerator works great, but most people don’t have access to aquaculture equipment. You can back a boat with an outboard motor halfway into the pond and tilt the motor at a 45-degree angle to the water surface. Run the motor at high speed to move a “rooster tail” of water into the air and across the pond. Any technique that mixes water and air can help provide an oxygen refuge for fish.
Following a severe fish kill, some fingerling fish usually survive, but overcrowding bream tends to follow. After a severe fish kill, contact a fisheries biologist to assess the status of your fish population.
pH and Mineral Problems
Poor water chemistry is the second-leading cause of fish death in Mississippi ponds. Fish in acidic water with low alkalinity and hardness are more likely to get sick, especially during times of stress, such as spawning season or periods of rapid temperature change, particularly late-winter and early-spring. A few fish, usually of different species (although catfish are especially sensitive), die every day, and many may have sores or lesions. If this is the case, have your pond water alkalinity measured to determine if agricultural limestone is needed. Liming increases the dissolved minerals in the water, which reduces stress on the fish.
Infectious Diseases and Parasites
Bream and bass generally do not have significant problems with infectious diseases in well-balanced ponds, although you may see an occasional sore on individual fish during spawning season or after an injury. This is normal, and these external sores do not pose any health hazard to humans.
The one known exception is largemouth bass virus (LMBV), which is not common in Mississippi ponds. This virus becomes evident during the hot summer, when largemouth bass are seen sick or dead on the surface and around the pond. A few bass die every day during warm weather, and larger fish seem to be more affected. When water temperatures cool in September/October, no more fish die from the virus, but the virus persists in the pond. The best way to avoid LMBV and other health problems is to follow stocking recommendations and to avoid stocking fish from other natural systems.
Occasionally, bass and bream have small white or yellowish grubs imbedded in the flesh. These grubs, although unpleasant to look at, pose no threat to humans. You can trim away the affected area, and the rest of the fish is safe to eat if properly cooked.
Infectious diseases and parasites of channel catfish are common problems in catfish ponds. Overstocking, inconsistent feeding, and poor water quality contribute to this in recreational ponds. Disease and parasite problems of catfish rarely occur when you use low stocking densities (100 to 150 per acre). Stress from handling may cause die-offs of fish within 2 weeks of stocking new or established ponds. If you choose to stock catfish at rates higher than recommended (100 to 150 per acre), plan to cope with problems that may occur.
Fire ants often wash into ponds or fly in during breeding swarms, and small and intermediate-sized bream may die from eating these insects. Bass are rarely affected. This generally does not hurt the population balance.
Determining Factors in Fish Kills
When a fish kill occurs, be ready to tell a fisheries professional the following information:
- Species and sizes that died.
- Number of fish lost since the die-off started.
- Approximate number of fish lost each day.
- Date and time of day the losses started.
- Whether fish were seen “gasping” at the surface of the water.
- Size of pond (surface acres).
- Average pond depth.
- Number of fish stocked in the pond.
- Condition and color of the bloom or water before and after fish kill:
- Light – You can see at least 18 inches deep, and the pond has no accumulation of algae in the corners or on the downwind side.
- Moderate – You can see 12 to 15 inches deep, and the pond may have some algae in the corners or on the downwind side.
- Heavy – You can see no more than 12 inches deep.
The primary purpose for many farm ponds is recreational fishing. With proper management, even small ponds can provide excellent fishing. One of the best ways to enhance the fishing experience is to create fish attractors at strategic locations in a pond or lake with a well-managed fish population.
Game fish such as bass and bream are attracted to cover or shelter of all types. Shelters provide areas where prey fish can hide from predators and where predators can find prey species. They also provide spawning areas and harbor large numbers of invertebrates and insects that small fish feed on.
Natural cover that provides shelter for fish includes ditches, creeks, trees (standing or tree tops), stumps, vegetation, and other irregular features of the bottom. In ponds where natural shelter for fish is missing or inadequate, you can establish artificial structures to act as fish shelters that will attract and hold fish.
Trees as Fish Attractors
You can develop fish shelters that will increase fish harvest and angling success in existing ponds with small trees such as blackjack oaks, post oaks, or cedars. Discarded Christmas trees make good temporary shelters, but they decompose quickly and must be replaced often.
For small ponds, bushy-crowned trees 10 to 15 feet tall are sufficient. You can use larger trees in larger lakes. In ponds smaller than 1 acre, one brush shelter is enough. Larger ponds need one or two shelters per acre. Select attractor sites anglers can reach. Good locations are in water 4 to 8 feet deep near creek channels, near points, or at drop-offs.
Drive a stake or use a floating buoy to mark the shelter site permanently. Place three to five trees at each location. Green trees will usually sink without weights. Some trees, such as cedar, will float. Add weights to these varieties to keep the shelters in place.
Many new pond sites have trees in the basin. Cut and salvage most of these, then cut and pile or burn them. You can keep some trees, bushes, and brush piles to use in establishing fish shelters. From 10 percent to no more than 25 percent of the pond area can have some tree shelter.
Leave bushes and trees in deeper water areas, along creek runs, and in the middle of ponds and lakes. Leave the trees in small clumps, then cut the standing trees about 2 feet above the normal water level, and anchor the brushy tops to the bases of the stumps. The tall stumps serve as permanent markers for the shelter locations. Do not leave trees or bushes in shallow areas, in narrow coves, or along pond banks, because these areas will become difficult to fish and may develop weed problems. Also, too much cover in shallow water makes it hard for bass to effectively feed on bream and prevents navigation of the entire shoreline by boat. Fish will immediately inhabit brush-top shelters.
Gravel Beds as Fish Attractors
Gravel beds are extremely attractive to bream for spawning, and bream will use these gravel beds frequently throughout the spring and summer. Select an area in water 3 to 4 feet deep that is convenient for fishing. Drive a stake to mark the spot, and place washed gravel (½-inch diameter) around the stake, creating a bed of gravel 4 to 6 inches deep. A 3- to 5-cubic-yard load makes a gravel bed 12 to 15 feet wide.
For best results, you can provide a frame to hold the gravel in place. If the frame is made of treated lumber or other material that can float, make sure the frame is securely anchored to the bottom. You can add gravel beds to flooded sites or strategically place them during drawdowns. Avoid sites that have a high silt erosion problem.
Other Fish Attractors
If trees or brush piles are not available, you can place other types of structures in the pond to attract fish. Developing irregular bottom features during construction, such as ditches and underwater dirt mounds, also provides fish-attracting cover and creates excellent places to fish. Humps that rise to 3 to 4 feet of depth and are surrounded by deeper water are fantastic fish attractors, especially in combination with brush piles or gravel beds.
The ultimate fate of many farm ponds is an unbalanced fish population that is undesirable to anglers and has little recreational fishing value. Once a fish population reaches such a condition, the best solution is usually to eliminate the resident fish and restock with a desirable combination of fish at recommended rates.
The easiest way to renovate a pond is to drain and completely dry the pond. This also lets you modify the pond or add habitat. If any pools of water remain in the basin, drain or poison them, because small fish can survive in these pools for a very long time and ruin your renovation attempts.
Also, many ponds were not constructed with a drain, and all of the water cannot be removed. These ponds will need to be chemically renovated. Rotenone is a fish toxicant registered by the Environmental Protection Agency for removing unwanted fish.
What Is Rotenone?
Rotenone is available at most farm and chemical supply stores. It is classified as a “restricted-use pesticide,” and you cannot buy it without a private pesticide applicator’s certificate. You can get this certificate through your MSU Extension county agent.
Rotenone comes from the roots and stems of several tropical plants. Rotenone keeps fish from using oxygen, but it does not remove oxygen from the water. Fish in ponds treated with rotenone move to the shallow water or to the surface of deeper water soon after exposure to the chemical. Fish species respond differently to rotenone, so it is a good idea to know what species you have before you treat the pond.
Rotenone breaks down when exposed to the environment. The breakdown is rapid and is affected by temperature, light, oxygen, and alkalinity. Most waters are safe for restocking within 5 to 6 weeks. In general, the cooler the water, the longer rotenone lasts.
Preparing the Pond
You can treat ponds of any size with rotenone, but it can be difficult to spread rotenone for an effective fish kill in larger ponds or lakes. It is also expensive to treat large volumes of water. For these two reasons, you will need to reduce the water area and volume as much as possible before treating. You can do this by draining the pond as low as possible with a built-in standpipe, pump, or siphon device. The less water you have to treat, the more cost-effective the treatment. Also, lowering the water level pulls fish out of their shallow water cover that can be difficult to treat.
How to Apply Rotenone
Rotenone is available in powder and liquid formulations. Liquids are easier to get into solution and are more reliable for total fish kills. The liquid formulations typically contain 5 percent rotenone, although some contain 2.5 or 7 percent.
Treatment rates for a complete kill vary between 0.1 and 3 parts per million rotenone, depending on the objective of the pond renovation and the species present. All formulations must be diluted with water and evenly distributed throughout the water column. You can spray the chemical over the pond surface or drip it into the prop wash of an outboard motor. The key is to have an even distribution; otherwise, fish may find “safe” areas and not be killed. Application in a random “S” pattern throughout the pond maximizes coverage.
The best time to eradicate fish from a pond for restocking is late summer or early fall. Water temperatures are at their highest at this time, and the weather is usually dry, allowing easy draining. Killing the fish at this time reduces the time between the kill and the restocking, which minimizes the chance the pond will be contaminated by unwanted fish before restocking. This is an important consideration, since letting in unwanted species can defeat the purpose for the renovation.
If you drain the pond, it is critical to poison all remaining puddles to kill any fish there. Many small fish can survive in these pools, puddles, or stump holes for a long time. You must kill all fish to have a successful renovation. Otherwise, these surviving fish can contaminate the new fish population, and the renovation will have been for nothing.
When to Restock
It is important to wait until the rotenone dissipates before restocking. If you poison in early fall, the rotenone should be detoxified by the time early winter rains come to refill the pond. A good general rule is to wait 1 month. A simple test can help determine when it is safe to restock. Place a few bream (bluegill or redear) in a small cage in the pond or in an aerated container with water from the pond. If the fish survive 24 to 36 hours, it is safe to restock the pond. Do not release these fish into the pond unless they are part of your restocking plan!
Turtles usually are not a biological problem in farm ponds, but they might sometimes compete with fish for food items such as crawfish, insects, or other small food items. They can, though, create a nuisance to anglers when they are caught on hooks and must be removed, when they take baits intended for fish on trot lines, or when they eat fish on stringers left in the water. Turtles also become a problem in ponds where fish are being fed, because turtles quickly learn that fish food tastes good and represents an easy and free meal.
However, turtles can be beneficial. Their greatest service is as scavengers to eat dead fish and other animals or to eliminate diseased or weakened fish. Except for snapping varieties, turtles do not capture many live fish and should not be considered a problem in this regard.
Before pursuing any type of control method, consider whether or not turtles are a genuine problem in your pond. Unless numbers are high and the interference with other pond uses is severe, it is probably best to leave the turtles alone. However, if you have significant problems, you may need to consider removing some turtles.
Shooting turtles as they bask in the sun or as they swim in the water is an old practice you should never use. Shooting into or across water is dangerous! Shooting also creates the possibility of killing a protected species, since identification from a distance is impossible. You can’t use repellents or toxicants, so trapping is the only choice.
Trapping can effectively reduce local populations. The best seasons for trapping are spring, summer, and early fall. Most turtles are inactive through the winter and feed very little, which makes baited traps ineffective during that time.
Although you can trap snappers and soft-shelled turtles using underwater baited traps, you usually don’t have to remove these species from a farm pond. The more aggravating species are the “baskers,” which often crowd together in large numbers on stumps, logs, or other structures above the water surface. By taking advantage of this, you can trap these species with a trap-box in the area turtles normally use. This trap has boards leading up from the water, with pivoting “balance boards.” When the turtles crawl onto these platforms, they weigh down the boards, dropping the turtles into the collection box.
Check traps daily and remove all turtles, then take the turtles to another location at least several miles away and release them into their natural habitat. However, understand that your release site is important, as you want the turtles to survive and you do not want to create a problem for someone else. Be careful not to violate state laws when transporting turtles, and do not carry them across state lines, since other states have different laws.
If you do not plan to visit the trap for a long while, flip it over on its side so turtles are not captured and left in the trap.
Other Problem Animals
Many animal species can take up residence on small lakes and ponds. Beavers, muskrats, nutria, alligators, and geese can be a nuisance or even cause damage.
Burrowing and damming activities can cause dam failure or flood adjacent landowners. Tree cutting and flooding can cause loss of valuable timber. Beaver dens or huts may be great places to fish, but it is at the landowner’s expense. Fish attractors can give the same success with no sacrifices.
Otters can quietly steal your fish at night. A family of otters, although cute, can virtually eliminate catchable-size fish in a small pond. The best control is immediate action at the first sign of these animals living in your lake. For species such as nutria, beavers, and muskrat, trapping is the most effective control. There are professional trappers that can assist. If an alligator is residing in your lake, contact your state management agency as this species is protected.