Causes of Fish Stress
sure that many of us have enough stress in our lives that
we laugh off the thought of our fish being stressed. But
a stressed fish is all too often a soon-to-be sick fish.
A fish that is stressed has a weakened immune system and
is thus much more susceptible to attack from parasites, bacteria, or other pathogens. Ensuring that your fish are
under as little stress as possible is the best thing you
can do to ensure a long and healthy life for your friends
with fins. This list of the 10 most common causes of fish
stress may help save your fish. (And if you still laugh
off the thought of fish stress just remember that if your
fish begin to die, that is one more stress factor in YOUR
Sudden changes in pH.
pH will always fluctuate
to some degree, but we want to have a pH that is as stable
as possible. Ensuring that the buffering capacity (KH)
will help keep a stable pH level. pH that is too high
or too low can also cause stress, but stability is what
is most important.
Sudden changes in water temperature.
Goldfish and koi are cold-blooded and can tolerate a wide
range of temperatures, but a sudden change in that temperature
can cause undue stress. Proper acclimation when adding
new fish is critical. Small, shallow ponds are more apt
to have the water temperature change quickly. Providing
good surface coverage will help keep the temperature changes
Insecurity. Fish can be stressed if they
are not comfortable in their surroundings. Clear water
with little surface coverage will cause a fish to feel
insecure. The fish are more susceptible to predator attack
in clear water and the fish is aware of this risk. Providing
surface coverage or an underwater hiding place can help.
Extra stress will be caused if the fish have actaully
been visited by a potential predator.
Fish need a regular balanced diet. This is not as complicated
as it may sound. While some packaged foods may have advantages
over other, as long as they are getting a regular feeding
of a seasonally-appropriate food labeled for koi or goldfish
they should be getting the nutrient they need.
Poor water quality.
Water quality is a broad term but is often referring mainly
to the nitrogen compounds found in the water. Ammonia, Nitrite, and Nitrate are always going to be present to
a degree in a pond with fish, but the levels need to be
kept as low as possible. Good filtration is the key to
breaking down ammonia and nitite. Nitrate is used up by
plants or should be removed with regular, partial water-changes.
Water toxin. There can be many, many
possible toxins coming from many sources that can stress
or directly kill fish. Chlorine and chloramines are common
additives to tap water that if not removed can cause severe
stress or death. Other common sources for toxins are lawn
fertilizers or pesticides that may blow into the water
or be washed in along with rain. If this type of toxin
is suspected an immediate water change would be called
Lack of sufficient oxygen.
Fish rely on dissolved oxygen in the water for respiration.
Common causes of a low disolved oxygen level are too many
fish, not enough aeration, or a large algae kill.
Overcrowding. Keeping too many fish leads
to many of the other issues addressed here including poor
oxygen levels and buildup of nitrogen compounds.
stress. Physical stress can be caused by an actual
wound. A fish can be wounded by a predator or scrape against
a sharp rock in the pond. Handling a fish also will cause
stress. Avoid catching fish unnecessarily.
Stress may lead to an infection from some sort of pathogen,
but an infection will also increase the stress level thereby
making the fish more susceptible to further infection
and limting their ability to fight it off.
You may also be interested in our article on Guarding
Against Sick Fish. See a listing of all our fish
Index of Fish Related Articles