Hi,
this is Heiko Bleher and I just wanted to add something in this long and very important thread:
I have seen governments, mostly the departments of the Minister of Fisheries & Agriculture, Bureau of Fisheries, their directors, sub-directors, etc., in those respective countries (without naming them, except 2 recent onesl here), who have released and continuously release exotic species into their native rivers and lakes. And from what I have seen during my travels and research in aquatic habitats of 166 countries so far, the damage those have done to the freshwater environments around the globe is ten-thousands of times worse then the few aquarium fishes aquarists or fishkeepers introduced.
In most cases the excuse is (or was) to bring "benifit" or "protein" to the rural people so they have fishes they can catch to eat. Just one single example (and I can give 100 more): Last November in the Pilippines I was invited by the Bureau of Fisheries to do research in two river basin and in one there was but two gobiids no more native fish species living except for very small introduce Tilapias (which do not grow anymore as there is no more food source for them - they have eaten up everything). They native fishes are history and the Tilapia do not bring any benifit to the locals anymore. And the Bureau of Fishes still introduces fingerlings of Tilapias in their rivers every year...
Have a look at:
http://www.aquapress-bleher.com/index.php?option=com_content&task=blogsection&id=3&Itemid=40
or go directly to:
http://www.aquapress-bleher.com/index.php?option=com_content&task=view&id=425&Itemid=40
Last month, Janaury 2010 I travelled 2500 km doing research on 50 freahwater lakes in Rajasthan, India, of which almost all were history (dry, global warming advancing 10-times worse then what is predicted) which can still be seen on google.com maps as of today. (That is how old google maps are...). The couple I found with water ahd only Gambusia and Guppies, no more native fish. And they continue (Governments) to introduce them against Mosquitoes, although for over 100 years we know that it does not work. It did not do anything so far in Central or South America, why should it help anywhere else in freshwater habitats to eliminate Mosuitoe larvae? But it is as with (almost) everything else: people who know about it will not be asked.
I find these recently again upcoming discussions by several organs (including in the OFI which I founded) in regards to "release of ornamental fish into the wild" over exaggerated. I wish someone in this world would step up and stop this crazyness of introductions of exotics done on the higher (Government) level around the world - and None-Stop.
Best regards from a collector and nature lover,
Heiko Bleher
www.aquapress-bleher.com