"Essay" on Drop Eye (from a physician/biologist)

[jcardona1]

Trauma does seem like a valid reason, but what do you guys think actually causes the eye to droop? there's obviously some buildup behind the eye that pushes it out, as i have seen this.

and what is it that keeps the eye straight, muscles? is it feasible to say that severa trauma to the head can tear the muscles behind the eye, allowing it to droop?

 

[Bderick67]

So the cases for trauma related DE seem awfully compelling. It's a great theory. I'd love to help us prove it correct.

So to elaborate on the trauma. This question is probably impossible to answer, but has anyone noticed what part of your aro typically strikes your canopy? I realize this is like trying to describe a lightning strike, but has anyone been lucky enough to have accurately witnessed (or better yet, filmed) this?

One caveat for us all: if this turns out to indeed be trauma related, I will feel truly sad. The reason is, if true, no matter how you want to look at it, drop eye suddenly becomes a preventable injury that is entirely our fault.

Here is a good article by Jay Hemdal on DE(of course he supports the Trauma theory). Eye-Droop in Arowana and Arapaima gigas »

Regarding what part of the head receives the trauma. Well the are two cases, for an aro that has left the tank and hit the floor you would see alot of hitting on the side as the fish is flopping. Within the tank the blunt force would come from straight on through the tip of the jaw and nose this being from a spooked aro with nowhere to go. There is also the less traumatic bumping of the top of head during feedings or even being spooked but just grazing the top structure.

 

[Scylla]

Um...I don't know too much about aros but why can't it be a combination of things that is causeing this. Maybe the head trauma triggers something that the silvers are more genetically prone to. Immune disorders can be triggered by trauma....
Also just because one has head trauma and doesn't develop DE doesn't mean that DE isn't caused by trauma. If two people close their fingers in a door it's possible that one could break their finger and the other doesn't.

Ah. You've touched on something I was hoping to bring up much later (if ever, for fear of deteriorating this conversation into chaos): the good old saying, "correlation does not imply causation."

This could be an entirely separate thread about scientific theory but my favorite example to illustrate this statement (similar to your finger breaking) is this:

There is a very high correlation between falling asleep with your shoes on and having a terrible headache 8-10 hours later. jcardona, your avatar is the answer to why the resulting headache has absolutely nothing to do with shoes!

Now obviously trauma is a very possible explanation for DE. But I've had to deal with statistics way too long to call it absolute fact yet. You are right, j. We need much more information and even then we still may never know. Buy hey, at least we're getting the ball rolling!

 

[Bderick67]

Trauma does seem like a valid reason, but what do you guys think actually causes the eye to droop? there's obviously some buildup behind the eye that pushes it out, as i have seen this.

and what is it that keeps the eye straight, muscles? is it feasible to say that severa trauma to the head can tear the muscles behind the eye, allowing it to droop?

This is were I think the lazy eyes thing comes in. Because of what I believe the eye muscle are not used enough in aquarium kept arowana so these muscle grow week. Maybe if the muscles week more active and strengthened DE would be less likely to happen or possibly the aro could even recover from slight DE.

Could be that trauma is a trigger and not a cause. I'm sure the cause is likely a combination of several factors.

 

[Scylla]

Here is a good article by Jay Hemdal on DE(of course he supports the Trauma theory). Eye-Droop in Arowana and Arapaima gigas »

Regarding what part of the head receives the trauma. Well the are two cases, for an aro that has left the tank and hit the floor you would see alot of hitting on the side as the fish is flopping. Within the tank the blunt force would come from straight on through the tip of the jaw and nose this being from a spooked aro with nowhere to go. There is also the less traumatic bumping of the top of head during feedings or even being spooked but just grazing the top structure.

Thanks Brian! What an excellent article. I'm starting to become a believer. Anyone have access to the British research article he was talking about? I'd love to read it.

 

[King-eL]

There is not much difference between blacks and silvers but you do acknowledge there is a difference. With the pond kept arows, I have not found any documented cases of silver aros raised in a pond with DE, the few with DE that are kept in ponds were tank raised and had the DE before being placed in the pond.

Have you ever seen an aro develop DE almost instantly? Meaning on day it was not there the next day it was. Myself and many others have, there has to be an explanation for this. With mine it developed very near after severe head trauma.

I have experience keeping them in their entire life in pond back when I was in Asia and still they develope DE. No need for document. Also some asian farms have them as well.

Let Koji jump in to this as he got some captive breed silver aro keep in a 6x2x2 tank with no DE.

 

[Aeroxide]

Just to throw this out there for the sake of discussion: People probably have a lot more contact with these fish in captivity as opposed to in the wild for obvious reasons. So, naturally there would be far more cases of DE observed in captive fish. Is DE a phenomenon that exclusively affects fish only in captivity? Is there any documented information that rules out the possibility of an arowana developing DE while in the wild?

 

[Bderick67]

I have experience keeping them in their entire life in pond back when I was in Asia and still they develope DE. No need for document. Also some asian farms have them as well.

Let Koji jump in to this as he got some captive breed silver aro keep in a 6x2x2 tank with no DE.

Intersting as this is the first I've heard of pond raised aros developing DE. Most reports are of the ponds even curring or lessening the severity of the DE.

Regarding Koji's tank, it really does not prove anything. There was a while back here on MFK some one found a 24"+ silver that had been raised in a 55g tank and had no DE. But who is to say if it ever experienced any type trauma or not.

One thing with Koji's tank though, with as many silvers that he has in that tank I would think that they would not suffer from lack of exercising their eye muscles. They would constantly have to be on the watch as to not be running into one another.

 

[King-eL]

Intersting as this is the first I've heard of pond raised aros developing DE. Most reports are of the ponds even curring or lessening the severity of the DE.

Regarding Koji's tank, it really does not prove anything. There was a while back here on MFK some one found a 24"+ silver that had been raised in a 55g tank and had no DE. But who is to say if it ever experienced any type trauma or not.

One thing with Koji's tank though, with as many silvers that he has in that tank I would think that they would not suffer from lack of exercising their eye muscles. They would constantly have to be on the watch as to not be running into one another.

My tank contain lots of fish as well more tha Koji's silver aro comm. Still my silver get DE. I also don't see any signs of bump or any injury around the head area and it never jump out and hit the floor. The DE started to develop when it's around 16".

 

[T1KARMANN]

has anyone ever thought it maybe some thing to do with water parameters

1 have kept many Asian aros 2 black aros and 1 jardini none of which have got drop eye

i know the black aros and jardini are not prone to drop eye so lets rule them out

Asian aros can get it but you would think out of 10 aro at least 1 would have got it

is it not possible that it has something to do with high PH or nitrates

I'm not 100% sure what the natural PH for a silver aro is but i think it would be lower than the 6.5-7 most of us keep our aros in

it maybe that Asian black and jardini can tolerate the higher PH better than silver aros