The most important group of introduced fish is the one of the salmónidos ones. These entered the country as of 1904 in a number of ten species, of which the four varieties of trout and the locked up salmon adapted. From 1980 they began to enter, by the river basins of pacific slope, marine salmons coming from the intense activity of piscicultura of Chile .
The carps and the tilapias were engaged in with culture aims. First it has colonized a great amount of atmospheres having degraded the quality of many of them.
Some observations of tucunarés in the dam of Yacyretá exist, which are descending from Brazil, country that has introduced it in the Paranaense river basin.
The reason is not known the appearance of some esturiones for sure in the Parana river. The registry is of very few units.