Eye Size Explained

[pcsb23]

When discus are assessed people often refer to a "nice size eye" or "the eye is too big" or "it has a small eye". I have been asked on a few occaisions to explain what is meant by a good size eye and a too big size eye.

In the picture there are 2 sets of of 2. The set on the left is of an oversize or big eye, the set on the right is of a good sized eye, in this particular case it is notable as it is on a wild caught discus. Wild caughts are often thought to have big eyes.

The left side of each set is the ey in all its glory, the right side of each set has size lines drawn on to help explain an often used term of 'eye count'. When I first heard this it made me think there could be a mutant discus with 7 1/2 eyes!!! (j/k )

On many of the newer strains of domestic discus the eye count is now heading around 9 to 9 1/2. In the older strains and wilds then 7 1/2 "eyes" is considered correct. It was Jack Wattley that originated this measure. The eye count is measured vertically.

I hope that helps in understanding eye size and its relation to the discus's size as well as the various terms used.

[Cosmo]

Paul,

Excellent post

But how did you get them to pose in front of the chart that way

Jim

[RyanH]

So if I understand correctly, according to Wattley, the diameter of the eye should equal about 1/7 of the total height of the head.

[Willie]

This post is better than anything I've ever seen in a glossy hardback!

As Paul indicated, the newer Pigeon Blood types were bred to have smaller eyes. I have seen Goldens and Tangerines from Asia with closer to the 9 to 9.5 ratio for body to eye. So when you judge eye size on discus, it's important to take the varietal type into account. Older strains like Turquoise and Cobalts have the 7 to 7.5 ratio.

Great job, Paul.

[brewmaster15]

Excellent Post Paul!

Thanks for taking the time to put it into words and pictures so everyone can understand!

-al

[pcsb23]

So if I understand correctly, according to Wattley, the diameter of the eye should equal about 1/7 of the total height of the head.

Ryan,

Yes thats correct, as Willie explains the newer strains go even more towards the 1/9th of head size.

[ShinShin]

Great diagram, Paul. This should help many understand more about this topic. Good job!

Mat

[John_Nicholson]

Great Job!

-john

[brewmaster15]

I really like this eyesize ratio explaination.. Its perfect Paul...

When I was in the lab I used alot of digital imaging and software to analize things... some was very expensive software..some was free... I like free

Theres a bit of software that I used that was great...it was free, easy to use and an awesome tool...Its called NIH Image...or for Pcs...IMAGE J.

It an be downloaded at...http://rsbweb.nih.gov/ij/download.html

Its quantatative software...has some great tool for measuring things in images....Theres a simple tool bar... I think this program would be great for everyone that wants to measure the eyes of their fish without the hassel of that hatch bar that paul used here...

Theres a tool called straightline selection...Its basically a tapemeasure that reads out in pixels ( what a digital image is made of) Draw the line across the eye, and measure the number of pixels in the eyes cross section...note the amount... then draw the line across the head and thru the eye as Paul has done..., again record the value in pixels..

Next divide the head value by the eye and it gives you the number of eyes in that Hatch bar paul used..

another words... In the Image Paul used to illustrate the 7 1/2 count..

I used the Image J program to measure...

The eye is about 48 pixels across
The head is about 340 pixels across if Drawn as Paul did..

Therefore 340 divided by 48 = 7.08 counts..

This will pretty much allow anyone out there to assess their fishes eye size and get pretty good results with little work... Try it and let me know what you think..

-al

Ps...you can do the same measurements with photoshop and other software...but the NIH program is free

[t2000kw]

Okay I was just grousing over in the 'what not to buy' list about no explanations re: what was wrong with the fish--apparently I've arrived where I need to be to learn these things.

Re: the size of eye: is this an arbitrary choice, like the breed statistics on a show dog or cat, or is there a good health/structural reason for prefering the small over the large eye--maybe it was actually in the thread and I read through it too fast?

I do get that a small eye is going to make a fish appear larger by comparison--is that it? Or is it truly arbitrary?

Melis (who, in her ignorance, kinda likes the big eyes)

[Squiggy]

Your confusion is understandable...

Discus eyes seem to grow at a uniform rate even when the fish doesn't. A large eye (proportionally) indicates that the fish has had growth problems somewhere along the line. It could have been due to any of the numerous factors...poor feed, poor water, illness, runting, etc...

hth

Joe

[Tony_S]

Melis...

Eye size is one of the main factors in assessing the previous care and future growth potential of a discus. It really has nothing to 'directly' do with the fish's health per-say....A sick discus can have large eyes, but so to can a healthy discus.

Basically its part aesthetic...part 'crystal ball'.

Tony