paku found in Illinoise

I found an article reporting on fisherman catching Paku in a lake in Illinoise.

http://www.grindtv.c...lake community/

Is this a new invasive to watch for, or will this tropical not be able to survive the winter.

People catch them occasionally in the Tennessee River in 'bama, with no evidence of a breeding population. It's the same old, same old of people getting fish that grow too big and finally doing the annoying thing of releasing them.

When I asked the DNR fisheries technician that I work with what the strangest fish reports have been, he said that at least twice or thrice a year there'd be a Pacu that some fisherman rolled in (predictably he will tell the newspapers that he captured a pirahna, and he usually caught the fish on a piece of bread). This just goes to show how common it is for an unsuspecting and ill-researched new fishkeeper to buy the "cute little fishy" in the store only to realize later that said fish has the potential to grow up to four feet long. They expect the aquarium fishes sold in fish stores to be, you know, good for the average aquarium. Zoos and public aquariums are swamped with requests to take in Pacus and other large fish (Red-tail Catfish, Bull Shark Catfish, you name it, even those nasty little "Chinese" [really Indian or Thai] "Algae-eaters" [try hicky makers]) that are commonly sold in fish stores, so they cannot take the fish in. Obviously, this person does not put forth the effort to investigate and find facts, so they finish watching "Finding Nemo" and decide to release the fish into a local body of water (it doesn't fit down the toilet drain by now). Yup, as long as Petsmart, Walmart, and even more credible stores that sell fish make money off of unreasonably large fish species, and continue to tell customers that their fish will "only grow to the size of their aquarium (hmm box-shaped fish anyone)" and the people remain uneducated, this trend will continue indefinitely. I'll bet if even a single commercial was aired on a well-watched network warning people to research their fish before buying them since not all sold are suitable for the beginner's aquarium, we would see a rapid drop in this behavior.

/end vent

Very interesting. Pacu is definitely a tropical species and I can't imagine it surviving a mid west usa winter. Recently I've discovered that we have a thriving population of asian "weather loaches" in nearby Lake Ronkonkoma, here on Long Island. While these might be considered
"tropical fish" because they are sold in pet stores as such, they evidently can do just fine in our temperate climate. They can overwinter and I'm told that they can aestivate should their habitat become dry. It remains to be seen how they impact the local ecosystem.

Sometimes the fishes reported as pirahna / pacu are in fact pirahna. A few years back I identified a fish as a red pirahna that was reported to the newspaper. A second opinion was desired from an expert, who indicated without seeing fish that is was a pacu which is what was published. Same expert later saw fish and acknowledged fish was in fact a pirahna. Info going out was not corrected so assumption is most likely to be pacu for subsequent captures.

Sometimes the fishes reported as pirahna / pacu are in fact pirahna.

Based on the teeth in the article this one is really a pacu. Pacu have creepy human-looking teeth. See picture in http://www.metro.co....-british-angler

Edited by EricaWieser, 01 July 2012 - 11:16 AM.

Most true tropical species won't survive in most waters of northern hempshire....however they can survive in hot springs or power plants. I know there is a breeding populations of tilapia, convicts and livebears in Montana.

As for the pacu story, this isn't new to us and it is really common thing. I once caught a common pleco up north of Brainerd, Minnesota few years ago. Recently when I was doing a survery on one of SW Minnesota lakes for IBI, my partner and I seined a young feral goldfish in that lake. I learned that a property owner on the lake has a goldfish pond few years ago before he drained that pond. Good news that it appeared that goldfish numbers were low and remained uncommon in that lake.

It seems likely to me that eventually a breeding population of convicts sustained by a very localized spot of warm water like that would eventually develop some cold tolerance. They breed in such fantastic numbers that they would always be overpopulating the warm area, and there is a significant difference in cold tolerance even among individuals from the same brood (I didn't mean to let their heater go out to learn that!).