Koi Stress Part 1: Symptoms
You know that stress is a part of everyday life, and you’ve uncovered methods of coping with the demands you face. However, you may not realize that your koi could experience trauma related to stress as well. Without your intervention, your fish may have difficulty overcoming the serious tension and strain that can result from specific triggers; this is koi stress.
Because of their size, koi appear to be very hardy fish, and they are when their environment is properly maintained. However, they are quite sensitive to sudden changes in their environment, which can cause undue stress.
Raising koi is in large part about managing the pond ecosystem so that it remains as stable as possible. Koi are happy in a consistent pond setting. Changes in this environment, in the water quality, or pond conditions can stress your fish. Even introducing new koi to your pond can cause apprehension and increase the demands on pond water, that can result in physical issues and sickness.
Every fish is different, and some are stronger than others when dealing with changes to the pond environment. Yet, if a problem goes untreated, eventually all of your koi will show symptoms of stress and may even parish. It is important to determine the cause of stress and improve the pond conditions as soon as any symptom of stress begins to appear in your koi.
Symptoms of Stress
You must be aware of changes in your koi that could represent a stressor within their environment. Without noticing these sometimes-subtle changes, you could be putting your fish in greater danger.
If you notice any differences in the behavior of your koi, they might be experiencing stress. Changes could include swimming sluggishly, refusing food, or consistently hiding in rocks, plants, or other crevices.
Stressed fish have a desire to break away from the group and hide away. They may slowly circle the bottom of the pond by themselves or disappear among the vegetation. You may notice that one or two koi are missing, because they do not show themselves when you are around – even at feeding time. They have most likely found a hiding spot where they feel safe and secure when hidden away. They may be too stressed to eat, or they may come out once you’ve gone to feed when it is quieter.
Your koi may also exhibit physical changes when stressed, including rashes, a pinkish color all-over the body and especially the fins, sores, or spots. These unfamiliar markings could be a sign of a bacterial or parasitic infection. Torn fins, damaged scales, and even cuts and blood spots could suggest problems with a predator. Koi are known for their vivid colors and patterns. On a stressed fish, the colors will slowly fade and lighten, becoming dull and subdued.
Common Signs of Stressed Fish
You should be observant of any changes in the appearance and behavior of your koi in order to effectively detect stress. This means that you must know what “normal” looks like in your pond. Visually examine your koi regularly, particularly their fins, which have a tendency to deteriorate when under stress. If you notice fins with tears, ragged or uneven edges, splits, or signs of reddening or red lines, then your koi are experiencing stress.
More signs of koi stress include:
- Constantly swimming at the bottom of the pond
- Reluctance to surface, even at feeding time
- Sluggish swimming with abnormal or convulsive motion
- Tilting on its side while swimming or floating
- Lying motionless on pond bottom
- Jumping or breaking the surface of the water
- Pink-ish coloration on skin and/or fins
- Dullness or reduced colors
- Hiding in plants, between rocks, under the waterfall, or in other crevices
- Separating from the group
- Scraping against rocks, pond edges and other items in the pond, as if scratching
- Fins held tightly against body, clamping
Your koi will show signs of stress when dealing with illness or parasites.
Koi Stress Part 2: Causes of Stress
Once you can identify the symptoms of koi stress, you must understand the cause in order to fix it. Oftentimes, the symptoms for different stressors are the same, so it’s not always easy to pinpoint the underlying problem. It’s a good idea to review each potential problem in an unhurried, progressive manner, ensuring that you are researching every possible cause and fixing potential problems as they become evident. Keep in mind that there may be more than one stressor affecting your koi.
Causes of Stress
Parasites are a fact of life in the Koi world. Any body of water that contains fish also contains parasites. Healthy koi can, and do, host parasites in small quantities. Only when fish are weakened and stressed the parasites are encouraged to breed excessively and flourish.
Parasites – such as flukes, anchor worms, and fish lice to name a few, can cause changes in both appearance and behavior. Parasites may be difficult to identify. A microscope is necessary for many koi parasite identification. Adult Anchor Worms and Fish Lice are visible to the unaided eye, but are quite small and easily overlooked.
Signs of parasite infestations are very similar to the symptoms of other stressors. If your koi exhibit any of the following signs of parasite infestation, you should consider implementing a parasite treatment:
- Rubbing on the pond edges
- Loss of appetite
- “Panting” or bleeding gills
- Pectoral fins that are held close to the body, even when swimming
- Foggy eyes
- Physical changes to the skin including:
- Patches of fungus
- Bumps, sores, and lesions
- Reddening of the skin and/or fins
- Tilting to their side or lying on the bottom of the pond
- Staying near high oxygen concentration areas
Predators are a common source of stress on Koi. While most backyard koi ponds are safe from predators, yours still may be subject to attack from predators such as neighborhood cats, racoons, ducks and birds, and even other more dominate fish. If your pond is near a wooded area, you may have a greater probability of natural predators seeking out your koi for a meal. Signs of being attacked by a predator include injuries, torn scales, and damaged fins. Your fish may also show typical signs of stress including darting, hiding, circling the bottom of the pond, or refusing food.
If your koi is showing signs of attack from a predator, you may want to check them for injury. You must be especially gentle so that you do not cause further stress or damage. You can use a shallow pan-net to gently guide your fish to the surface of the water and fully check it for injuries. If you need to transfer the koi to a small aquarium for treatment use a soft water-holding sock net to move the fish safely.
New Pond Stress
One of the biggest stressors for koi is being introduced to a new environment. Koi are affected by change and often become stressed in a new pond until they become accustomed to their new surroundings. If you are moving your koi to a new pond, be sure that the water is cycled correctly prior to introducing the fish to it. Be sure that you properly introduce new koi to an established pond. Initially, it is normal for koi to hide and not eat with the group; however, with time your koi should become acclimated and act normally.
Water quality is a major cause of fish stress. Stability of the pond water is essential to maintaining koi health. Even a gradual change in the water quality can cause your fish to show signs of stress. Causes of shifts in water quality can range from differences in:
- Ammonia: A result of waste in the water
- Nitrites: Nitrosomonas, a good bacteria, converts ammonia into nitrates
- Nitrates: The final product in the reduction of ammonia
- pH: Algae switches to respiration at night, discharging carbon dioxide into the water, thereby acidifying it
- KH: The measure of the Carbonate Hardness in the water (the amount of Calcium Carbonate)
- Oxygen: Dissolved oxygen (DO) level is measured in mg/L, necessary for fish life
Monitoring these parameters is important, so that they do not become severe and cause excessive stress on your koi.
If stalked by predators – such as cats, hawks, herons, and raccoons – koi will begin to hide more often and may show signs of stress and injury, such as gashes, torn fins, and spots of blood. If not deterred, predators will continually return to your pond. Fish will feel more stressed the longer they feel threatened, and if there are no sufficient hiding places within their environment, they will not feel safe at all. Be sure that your pond is deep enough for fish to flee invaders, or provide hiding places such as a cave to provide protection.
Other potential stressors can be broken into three categories, including chemical, biological, and physical:
- Poor water quality: improper pH or low oxygen levels
- Pollution: Incorrect water treatments or insect spray contaminants
- Diet: A composition with an imbalance of proteins or amino acids
- Nitrogenous wastes: Metabolic wastes including an accumulation of ammonia, nitrite, and so on
- Population: Overcrowding of the pond
- Other fish: Aggression and territorialism
- Microorganisms: Pathogenic and nonpathogenic sources
- Macroorganisms: Internal and external parasites
- Temperature: Drastic fluctuations may influence the immune system of koi
- Light: Intense sunlight may cause damage to delicate skin, a.k.a sunburn
- Sounds: Sudden and abrupt noises are often amplified in pond water disturbing fish
As a koi hobbyist and pond owner you should provide the most stress-free environment for your fish possible. Preventing causes of stress is much easier than dealing with the results of it.
Koi Stress Part 3: Solutions for Treating Koi Stress
There are many potential stressors that could affect your koi, and there are just as many solutions to these problems. It is a good idea to maintain a journal for your pond and fish. Both positive and negative occurrences should be recorded. Your journal will be an invaluable reference tool when attempting to pinpoint a potential problem.
Test Water Quality
If you are unsure of the cause of stress in your koi, you should begin by testing the pond water. A sudden change in pH, oxygen, or ammonia could be causing the stress. Commercial water test kits are available which can be used to test for imbalances in ammonia, pH, nitrites, nitrates, and oxygen, as well as KH and GH.
A rapid increase or decrease in pH can kill koi. Your pond should remain in the range of 6.5 to 7.8. Ammonia tends not to spike, but can gradually build up over time, wreaking havoc on your pond inhabitants. Be aware that ammonia’s toxicity is dependent on the pH levels and water temperatures, so as the pH and temperature rise, the deadlier the effect of any lingering ammonia.
Monitoring water quality should become routine, just like your general maintenance on your pond. Clearing sludge from the pond bottom, removing debris, and backwashing the filter should become regular maintenance. Also, check your aeration methods to ensure adequate oxygen is provided. Consider adding more to increase oxygen levels, which along with beneficial bacteria, will break down waste.
Remember that stability is important in koi, so do not cause drastic changes when fixing water quality issues. Make gradual adjustments to return the water parameters to desired levels.
Ideal Water Parameters:
|Oxygen Content||7-12 mg/L|
|Ammonia||0 – 0.01 mg/L un-ionized|
|Nitrite||0 – 0.01 mg/L|
|Nitrate||0 – 20 mg/L|
Treat for Parasites or Infections
When you suspect a parasite or bacterial infection is causing your koi stress, treatment is often necessary to destroy the parasite, improve healing, and strengthen the immune system. Bacterial infections are often secondary, as a result of parasite activity. While your koi may still show signs of stress during the healing process, they should return to their normal behavior patterns as they begin to feel better.
Common infections seen in koi are fin and tail rot, and ulcers. Ulcers are generally caused from parasite damage to your koi’s skin. In cases of injury or illness, it’s important to treat the pond to prevent infection and the growth of harmful bacteria, which could affect your healthy koi. The abrasions left behind by parasites are an ideal area for bacteria to invade and cause havoc. most treatments for these problems are safe, even for fish without an illness.
Parasites are often difficult to spot, but are easy to treat. A wide range of solutions are available that are safe for fish and can be used when parasites are suspected or even as a regular preventative measure, however, the best treatment is prevention. Most koi keepers will regularly treat their pond twice a year at the end of Summer and the start of Spring.
In addition to regular preventative treatments, choose only high-quality fish food formulated for the nutritional demands of Koi. A diet should be complete with vitamins, proteins, and fats to help keep your koi healthy. Healthy Koi are more likely to combat parasites and stress.
Depending on where you live, you may have a variety of predators seeking an easy snack from your pond. Even if you don’t see the intruder, you may be able to deduce that one has been by from various signs, including tracks, droppings, trampled plants, missing fish, and stressed or injured fish. Koi may refuse to feed while you are there, as they associate your presence – particularly your shadow across the pond surface or any unusual sound as the existence of a dangerous predator.
While providing a place for your koi to hide is important, you obviously want to address the predator so that you can enjoy watching your koi swim safely once again. Removing or deterring predators depends on the type of animal that is interfering with your pond. However, you can try sprinklers, decoys, netting, noise repellents or various other options available.
When your koi can relax and feel safe, they will stress less often. Shelter can be made with natural materials, such as rocks and plants, to create nooks and crannies for your koi to hide themselves when feeling stress or fear. Water lilies are floating plants that cover a large surface area, may prove places for fish to seek shelter. Unfortunately, plants do take some time to grow to their full potential, and in the meantime, you must use some other source for safety. Rocks can be stacked to create crevices and caves, so long as you are sure that they will not tip, possibly crushing or injuring your fish.
Improve Aeration and Filtration
Koi in a clean and highly oxygenated pond are less likely to be stressed. Not only do fish require oxygenated water to live, but beneficial bacteria utilize high levels of oxygen to break down waste and keep a pond clean.
Aeration and filtration systems also help improve water flow, thereby decreasing the chances of stagnant water. Waterfalls and fountains are not only decorative, they also help aerate your pond water, transferring nutrients and oxygen throughout the entire habitat. Ensure that your filtration system effectively removes debris and harmful agents such as ammonia.
Regularly clean your systems and your pond. Monitor water quality, treat for parasites and protect your pond from predators to ensure that you maintain a healthy & stress-free environment for your happy koi.