Worlds largest freshwater fish

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Well, but this doesn´t prove anything. As I wrote in the very first comment in this thread, this widespread dates come from one single hearsay report of the early 19th century. There was never a confirmed report of such a big arapaima, only because this was the very first description of the Arapaima at Europe, all other authors copied the dates. As this dates are absolutley obscure is already clear, because the length-weight-relation is completely out of proportion. The 180kg is probably really around the maximum weight this species can reach, they will become perhaps even a little bit heavier. But not that long.
 
I figured since they had the world's largest Amazon based aquarium display an a rather large collection of arapaima with a lot of time spent learning about them as a species (at all stages of growth), that they might have the background to justify the information they are putting out there for the general public. Maybe that is just me, though.
 
There are a lot of things which are not true and still very wide-spread. The Aquarium of Berlin also houses some arapaimas and wrote on the homepage that they can reach the nearly always cited 4,5m and 200kg. I wrote to them and told them the background of the dates as well as the actual dates of the largest recorded specimens and the length-weight relations, and they absolutley agreed with me.
This 4,5m and 200 or sometimes 180kg come all from the same original source, and are not based on actual examination. Schomburgk never saw himself a 4,5m arapaima, so I would really not take this too serious, especially given the ridiculous low weight. This is really not a good account for doubtlessness.
To give another example. Yesterday I looked at a book in our local university library about the fishes of the world. The book is really great, but I found again a fatal error. They wrote the wels catfish would COMMONLY REACH LENGTHS OF 3M.
But well, even given the fact that it is written in an academic standard book for ichthyology, this dates are completely false. If 3m would be common, why is the confirmed record only 2,78m? And this was a really exceptional and freakish monster-specimen, which was extremely over the average.
It happens actually comparably often that even scientists use very old and unconfirmed dates woithout any own research.
 
My guess is on Arapaima Gigas.
Many people say White Sturgeon, but I think it's originally a sw fish that can adapt well to freshwater. Wells catfish don't grow as big as an arapaima. also the wells catfish is prety good to addapt to brackish water but definately not saltwater.
 
As I already wrote, the problem is that the arapaima doesn´t grow as big as you can often read. The giant mekong catfish reaches much larger weights, and at least for the chinese paddlefish there are longer total lengths. So it is neither the longest nor the heaviest freshwater fish.
 
Hello all. Not many posts here. My monster fish tank is still a few years in the future. Have enjoyed this thread. The largest freshwater fish? Well, here are the authenticated record sizes.

alligator gar (Atractosteus spatula) - 114 inches, 365 pounds in 1991
Asian FW whipray (Himantura chaophraya) - 94 inches dia., 441 pounds in 2007
piraiba (Brachyplatystoma filamentosum) - 93 inches, 313 pounds in 1999
wels (Siluris glanis) - 109 inches, 317 pounds in 2000
Mekong river giant catfish (Pangasianodon gigas) - 106 inches, 645 pounds in 2005
arapaima (Arapaima gigas), pictured below - 98 inches, 330 pounds in the 1990s
After several days of searching, I could find no authenticated record of size in the Chinese paddlefish. However, the preserved specimen in the picture below shows it competes favorably with any of the others, possibly exceeds them.

Here's the source:http://http://www.fishing-worldrecords.com/photo_gallery1.htm

With no authentication, sorry, but 14 foot arapaima, 12 foot piraiba, 12 foot alligator gars and 1000 pound rays are heresay, nothing more. A 14 foot arapaima or 1000 pound ray requires more than a testimonial on a website as proof.;)

I left out all anadromous species since the thread seems to be geared toward completely freshwater species. So, based on factual evidence open to access by all involved parties, the alligator gar is as large or larger than the arapaima and the Mekong river cat far exceeds either in weight. The ray weighs more than any except the Mekong river cat, and the piraiba and wels both rival the arapaima and the gar. Title for largest easily goes to the Mekong River cat. The paddlefish is a wildcard.

Thought I'd throw in my unasked for 2 cents.

WYte

chinese-paddlefish-museum-ga.jpg
 
Acheloos;2466905; said:
As I already wrote, the problem is that the arapaima doesn´t grow as big as you can often read. The giant mekong catfish reaches much larger weights, and at least for the chinese paddlefish there are longer total lengths. So it is neither the longest nor the heaviest freshwater fish.

Bingo, Acheloos. Many factors can distort perception of just how big a critter is. People will often see what their preconceptions "tell" them they should see, regardless of evidence to the contrary.

WYite
 
Yes Wyomingite, that the thing. Only because there are STORIES about outsized specimens, this doesn´t mean they are true. I have to say that there are some corrections for your list. The largest confirmed wels was even 2,78m and 144kg, but it was not regarded as a fishing record. I contacted the taxidermist which worked on it, and this fish really existed.
To find good background information about the chinese paddlefish is really hard, and I am highly sceptic about the often claimed size up to 7m. My friend Cameron McCormick once wrote about his blog about this issue, I could imagine this could be interesting for you: http://cameronmccormick.blogspot.com/2007/07/megafishes-chinese-paddlefish.html
Here is also a very interesting pdf with a lot of rare photos of the giant paddlefish, including a specimen of 3,3m and 117kg. This is probably the longest actually confirmed freshwater fish of the world, surpassing even the arapaima, the wels and the mekong catfish. Given their extremely low population, there were surely specimens bigger than this one, even if we keep in mind, that they were most probably not the 7m monsters we can sometimes read.
 
2.78 meters is 109 inches, 144 kg is 317 pounds, both rounded to the nearest unit, LOL. Same fish, I bet, as that website acknowledges records not taken on rod and reel as well, Acheloos.

I'll check out the website on the paddlefish, thanks for the link. I agree it is/was a definite contender. Sadly, I doubt any still live. I've an interest in tales of animals of all types that are huge beyond the norm. 30 foot crocs, 45 foot pythons, etc. IMO, its a psychological phenomena; humans need monsters. In this age of reason and science, with no dragons or Chimaeras, yesterday's written exaggerations are today's myths.

WYite
 
what about the loch ness monster? jkjk
 
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