Introduced species in fisheries and aquaculture
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The FAO Database on Introductions of Aquatic Species (DIAS) was initiated by R.Welcomme in the early 1980s. This excellent resource on mainly freshwater fish introductions formed the basis for the 1988 FAO Fisheries Technical Paper no. 294.
The database has since been expanded to include additional taxa, such as molluscs and crustaceans, aquatic weeds, and marine species. In the mid-1990s a questionnaire was sent to fisheries experts to collect additional information on introductions and transfers of aquatic species in their countries.

If you are aware of introductions that are not yet included in DIAS, we welcome your information. Please use the reporting sheet to describe each introduction. Data on the introduction process and its effects should be collected and made available to the international community, so that lessons can be learned from positive or negative experiences. FAO's DIAS gives the possibility to share your experiences with the international community and represents a point of reference for considered introductions in the future. Nile perch, Tanzania The introduced Nile perch, by many considered an unwanted introduction, is appreciated especially on international markets.

Introductions Database

The FAO Database on Introductions of Aquatic Species (DIAS) is the primary information source on those species that have been introduced around the world and provides a brief review of the reason for their introduction, the responsible entity for the introduction and their impacts.
Go to website DIAS

Using DIAS

There are several ways to access the DIAS information, please read carefully which option is best for you.

  • If you have a good internet connection, we recommend the on-line version. Here you will find the most recent information, and many links to other fisheries resources.
  • DIAS will only work on Windows machines, users of other operating system can access the on-line version only
  • DIAS requires MS-Access 2002. If you have this installed on your machine, you can run DIAS from the CD-ROM.
  • If you have no MS-Access on your computer, but you have a version of MS-Windows XP or 2000, you can install a runtime version of MS-Access. Please click on setup.exe. If the installation does not start automatically, you can click on the file setup.exe in the package folder of the CD-ROM and follow the instructions. You need to have the proper rights for your computer to do this. The installation may take several minutes to complete.
  • To start the application after installation, go to Start/Programs/DIAS-V1-3/DIAS-V1-3 and click on the icon.
  • To uninstall the application, go to Start/Settings/Control panel/Add remove programs. Remove the DIAS-V1-3 application. Make sure that you close DIAS before you uninstall.
  • Even without installing DIAS, you can browse the contents using a spreadsheet program such as MS-Excel to click here for a spreadsheet version of DIAS. Please note that the spreadsheet doeas not contain all information of DIAS. E.g. the references are not included.


The Database on Introductions of Aquatic Species (DIAS) is being coordinated by Devin Bartley ([email protected]) of the Inland Water Resources and Aquaculture Service of the FAO Fisheries Department.

Local fisherman. Fisherman in Kenya.

Data collection coverage

The database includes records of species introduced or transferred from one country to another and does not consider movements of species inside the same country.
DIAS can provide a registry of where aquatic species have been introduced and some summary statistics. Some example maps demonstrate the extent of introductions.

FAO / FIRI, 2006