The true size of Arapaima gigas

[arapaimag]

Acheloos thank you for your thread and such informative and articulate posts.

Ramesh and Fishing Thailand I enjoyed and thank you for your knowledgeable contributions.

I too feel that in time the large fishing/breeding pond/lakes might get the future monster Pima recordholders of 3m or more. That could be in Thailand, Malaysia, other Asian countries or in the Americas like Brazil, Peru, Belize etc.

Your thread has been a myth buster and reminds me of the last line in this passage from Lucretius, my favourite philosophical poet

Look at a man in the midst of doubt and danger,
and you will learn in his hour of adversity what he really is.
It is then that true utterances are wrung from the recesses of his breast.
The mask is torn off, the reality remains

 

[Acheloos]

I just bought a short time ago a book about osteoglossiformes by Karl-Heinz Lüling (I mentioned him already in the very first post of this thread), who examined the arapaima in its natural habitat. He wrote that in most regions the average size was nearly exactly 2m, sometimes a little bit more. He also wrote that the old hearsay-claims of 4,5m is highly unprobable, and believed that the maximum lengths are about 3m. In regions with strong fishery, specimens of 1,5m were already rare.

 

[arapaimag]

I believe that Dr. Karl-Heinz Lüling of the Zoologischen Forschungsinstitut und Museum A. Konig in Bonn Germany is still considered the greatest authority of Arapaima gigas to have ever lived in the world for his 12 month study on them in Peru.

The famous fish enthusiast and National Geographic funded ethnologist Harald Schultz of the Museu Paulistra Sao Paulo, Brazil described him as such in articles on A.gigas Schultz wrote in the 1958 to 1961 period.

In late 1958 Schultz who spent many years in the Amazon traveled up the Japura river to meet the Maku indians (of the blow gun and poison dart fame). He describes the many ways the natives were already reducing and endangering the population of the A.gigas. From the commonly seen 2 person boat and harpooning. To the sometime up to one month kill in an area of every living of adult A.gigas using the “Fisga” method, the illegal and deadly “curral” method and the 30 foot ground net method.

Schulz describes a typical days catch in curral that he witnessed as being: “Three were small about 3 foot long and there were four giants 5 to 6 feet long.”

This shows that a man who spent many years of his life studying in the Amazon considered 5 to 6 foot A.gigas to be giants even in 1958.


The earliest realization of the depletion of A.gigas and subsequent captive breeding of them to replenish stock was by Dr. Carlos Estevao the late Director of the Museu Paraense Emilio Goeldi in Belem do Para in the first half of the 20th century. He actually did the captive breeding in ponds on the university grounds and also introduced about 10,000 of the fry to northeastern Brazil where they had become native by 1961, according to Schultz.

 

[Acheloos]

There is also photo in the book which shows a very big specimen caught by fishermen, somewhere in the 2,5m region (but it is hard to estimate the correct length, as the people there are often comparably small). There are also some very interesting dates of specimens from zoos with dates of length and weight, and they were really measured and not just estimated.
I own also a very good book written by Lüling about lungfishes.

 

[Ramesh]

Arapaimag, I agree I have really enjoyed this thread and thank Acheloos for starting it.
I studied science at Uni and have a degree in evolutionary biology and stongly agree that impirical evidence is always the gold standard in field biology.
Observations coupled with pictures and accurately collected measurements and data are always better the anecdotes and memory.
In the case of this truely great species the anecdotes and the hard data simply don't match up.
The largest animals would be expected to be found in the closed systems of the large Asian lakes and while some very large fish pushing 2.7m+ have been caught none have come anywhere near the sizes often mentioned for this species.
I agree with yourself and Acheloos that 3m would be towards the upper limit for this species with fish of 2.7 plus beening very rare and special.

 

[gigas12]

Hi,yes I agree,with the destruction of their natural habitat and great pressure caused by over fishing,today it would be really hard to see a.gigas that measure 3meters or more.

 

[Acheloos]

You have to keep in mind that lengths in the 2,5m region were already extraordinairy in regions without commercial fishing, and there are still such regions, which can hold record-animals like the one Janus Vagner caught.

 

[polish]

Well I am still not convinced they can't reach at least 4 meters but I do have this to add.

I just spent the entire morning looking through 110 pages of Google image search results. 55 pages for the word Pirarucu and 55 pages for the word Arapaima Gigas, I couldn't find any images of one that is larger then whats already posted in this thread and others. That doesn't mean they don't exist but I really wanted to find proof. I did find one small 100x100 pixel image of one that looked to be at least 10ft (3m+) but it couldn't be enlarged and when opening the page the image isn't there. It only showed up in the image results as a tiny thumbnail. However being that small of an image I didn't bother saving it because there would be to much speculation as with all the photos already posted. I was hoping to find one with a measurement but couldn't.

I'll continue my search but it's not looking good for me. Especially after watching the different shows on Discovery channel featuring Jeremey Wade and Zeb Hogan where both had a difficult enough time just catching one, let alone a monster. They may have been fished out so much that there are so few monsters left they'll never be seen. I also noticed on a few of the Amazon fishing sites they only list max size at 3m or 9ft. Perhaps this is just because it's the largest they've ever caught or they beleive that is as large as they get desite many other sources claiming 15ft is possible.

The debate continues...

 

[Ramesh]

It's basically called an over estimation or exaggeration and is a very common artefact of early feild biology and often occurs in species that are awe inspiring and have the ability to capture peoples imaginations.

Many animals such as Tigers, Lions, Elephants, Great White sharks, large constrictor snakes, whales, large Cephalopods and Crocodilians all have accounts of extremely large animals being recorded in literature.
Many are simply errors in observation/measurement or simply the former explaination.

 

[chrisdef15]

I cant believe this stupid argument as gone on as long as it has. Ofcourse there could be or has been bigger Giga's out there.

As has been said fish basically grow there whole lives. I dont care about the semantics of they slow down ect. Big deal, fact is they keep growing.

Alot of these "giant fish" caught in Asia have only been there (according to the guys in this thread who claim to work there) less then 20 years. That could be only half of there lifetime meaning they have plenty of growing to go. From what ive seen alot (not all) of these fishing parks and ponds are WAY more heavily stocked then nature, probably not exactly providing ideal growing conditions even if they are fed pellets ect to beef them up.

And overfishing (and pollution, habitat dectruction ect) would have wiped out alot of the big guys from the wild. Its highly likely there where massive 4-5 meter Giga's in the wild 100 years ago when the claims where originally made, same with catfish species, sturgeons, and even croc's ect but since it takes 50 years plus pristine conditions to get that size it doesnt happen much anymore these days as they get caught or killed before getting to that size.