|1. Background and Introduction
An Arowana is said to have droop eye syndrome when its eyeball is perpetually
tilted downwards such that it is always looking down. This usually occurs
in only 1 eye, with the other eye looking normal. The severity of droop
eye may vary from a slight tilt to an extreme case where a large part
of the top of the eye ball is exposed.
There are also cases where both eyes are tilted downwards. Usually the
degree of eyeball tilt is very mild in these cases and this occurrence
is also known as "slanted eyes" to some. An Arowana may be said
to have "slanted eyes" when both eyeballs are tilted slightly
downwards. It is debatable whether these Arowanas have slight droop eye
on both sides or "slanted eyes". Is the "slanted eye"
look, a mere coincidence of slight droop eye on both eyes, such that the
Arowana has a more balanced look? Thus, the special term "slanted
eyes" is used rather than droop eye? This could be something that
the reader might wish to ponder over and reach his own conclusion.
The occurrence of droop eye in Arowanas is an issue that is still very
much open to debate. To date, some have attributed this syndrome to genetics,
while others say that it's caused by diet and there are also some who
feel that it is the environment that causes this.
Arowana enthusiasts have classified the droop eye syndrome to be one
of the possible "defects" that an Arowana may posses. The other
possible physical defects that are common and unique to the Arowana include
protruding jaw, tail biting and pimple-like growth on the barbels amongst
others. The presence of these defects affect the overall beauty of the
specimen and thus to a certain extent, the value of the fish.
As the commonly quoted saying goes,"Beauty is in the eye of the
beholder." To what extent do these "defects" affect the
overall beauty and poise of the specimen is indeed highly subjective and
will not be discussed in this article. Suffice to say that under competition
standards, the occurrence of these "defects" are taken into
consideration during judging. However, as hobbyists, the extent to which
these defects are deemed disturbing will depend very much on the individual's
2. Causes and remedies of droop eye.
It has been said that high fat diet causes fatty deposits to be found
behind the eye socket. Perhaps autopsies were done on specimens with droop
eye and these were the findings.
1.5 Red with no droop eye
b) Same 1.5 Red while chewing on a feeder Goldgish
Photo credit: Edwin Chan
Another diet factor that has been mentioned is the feeding
of hard food. I would suppose that this theory comes along because it
was observed that the Arowana appears to be "looking down" when
chewing due to visual effect of the "flaring" gill plates. But
are the Arowana's eyeballs really looking down or just appear to be looking
Genetics could very be the cause but its very difficult to prove it right
or wrong. But whatever it is, any scientific hypothesis that cannot be
proven wrong may more or less be presumed right until proven otherwise.
Another genetic possibility could be the varying degree of inquisitiveness
of each individual fish. Just like humans, each individual fish has its
temperament and character also. Perhaps individual Arowanas that are more
inquisitive may be more prone to droop eye.
Environmental factors have been attributed to cause droop eye in Arowanas.
Among these factors are the reflection on the tank bottom and bright lights
at the top of the tank. As the aquarium lights are turned on at night,
we may observe that the Arowana's eyeballs may tilt down by as much as
about 30degrees. Could the bright lights at the top, be a factor that
causes this syndrome? Perhaps. Then again, if you were to suddenly turn
on the room lights, when the room is pitch dark, I too would squint my
eyes until my vision can adjust to the bright surroundings. What more
can we expect from fishes when they do not have eyelids?
How did reflection at the bottom of the tank become a factor associated
with this syndrome? This could have come about because under natural surroundings,
this reflection is not present. This reflection is present only in the
glass aquarium due to the highly polished surfaces. Since this is a factor
that is only present in artificial surroundings like glass tanks, it is
also presumed that it causes droop eye. Further evidence that support
this theory is the possibility of "curing" droop eye by placing
it in a fibreglass tank. However, fibreglass tanks are also used to prevent
the Arowana from peering out of the tank. As the normal glass aquarium
tanks are place a certain distance from the ground level, it is inevitable
that the Arowana will look downwards. Another alternative to remove reflection
at the tank bottom is to use gravel or set up a planted tank. Arowanas
are usually kept in bare tanks for easy maintenance and thus, usually
a thin layer of gravel is introduced as a compromise.
Another often cited possible cause for drop eye is the habitual looking
down by the Arowana. Arowanas being highly intelligent fishes, as intelligent
as a fish can get I suppose, are also inquisitive as well. As the fishes
are placed in tanks higher up, they also have a tendency to look down
on moving objects much akin to peering out of the tank. These may small
children and pets such as small dogs. As such, to minimise this "habit"
of looking down, people have proposed to place these Arowanas with slight
droop eye in to earth ponds, fibreglass tanks and also to cover all sides
of the glass tank up, leaving only the top surface visible. Such techniques
have been met with varying degrees of success.
the Arowana in a planted tank is a good way of removing reflection
from the bottom surface of the tank.It provides a natural setting
for the Arowana to reside. Maintainance may be a little more demanding
but the visually pleasing result makes it worthwhile if one can spare
Other cited possible cures are to place a ping-pong ball or two in the
tank. This will attract the Arowanas attention and entice it to look up.
However, I feel that this method will only attract the attention of the
Arowana for the first few days. Once the Arowana gets used to having this
boring in animate object floating around in the tank, it will simply ignore
it. Another one is the use of blinking lights placed on top of the tank.
Perhaps this may be a better method since the lights are at least moving.
These blinking lights may be in the form of bicycle lights or those decorative
lights commonly used for Christmas or Hari Raya decorations. I would prefer
those Christmas lights as they are less monotonous and more attention
grabbing. The Arowana is more likely to stay interested in these lights
much longer than with ping-pong balls. Nowadays, these lights even come
with sound and different blinking patterns. Imagine your Arowana listening
to Lambada all night long!
Another possible cause of droop eye is the introduction of bottom dwelling
tank mates into the Arowana tank. I feel that tank mates are fine and
good as they maintain a high activity level in the tank. These tank mates
have the similar effect on the Arowanas much like that cited for small
pets and children.
In conclusion, I would suppose the most politically correct answer is
to consider all factors when deciding how one should go about designing
their Arowana tank and routine. This would include the tank location,
the environment such as the number of viewable tank sides, tank height,
outside surroundings, feeding, etc.
If you do attempt to rectify the droop eye problem, try to do it as early
as possible. It has also been said that chances of success are better
when the droop eye is slight. Once severe droop eye sets in, rectification
is difficult, if not impossible. However, be aware that there are also
reported cases of recurring droop eye after it has been "cured".
Perhaps, this could be due to unresolved environmental or feeding issues.
If the cause of droop eye is indeed genetic, little could be done to prevent
it and hobbyists could probably rectify the problem when they notice it,
should they choose to do so.
These methods have worked for some and disappointed others. Whatever,
the case, do note that these "cures" could take anything from
weeks to months. Thus, patience is an important aspect when using these
methods to "cure" droop eye.
All in all, let's live and let live. Have fun keeping the majestic Dragon
Fish and don't be so bothered by these defects. After all, there is so
much more to the Arowana than just its eyes.
All these information have been compiled from the books that I have read
and also the many people who have been teaching me stuff on Arowanas and
general fish keeping, on and off the net, You know who you are, sincere
thanks to all.
I am also grateful to the fellow Arowana enthusiasts who were kind enough
to contribute their photos for this article.