Decree No. 509 of 1991 on the prevention, limitation and eradication of disease in aquatic organisms.

The text consists of 19 sections, divided into 9 Chapters: Scope and definitions (I); Aquatic organisms (II); Operating a breeding installation (III); Control of parent animal and related matters (IV); Sale, transfer and release of living fish and roe (V); Treatment of waste, used equipment, etc. (VI); Special measures for the fighting of diseases (VII); Exemptions and appeal (VIII); Penal provisions and entry into force (IX).
This Decree establishes measures to prevent and limit the spreading and eradication of infectious diseases in aquatic organisms. "Aquatic organisms" are defined as all animals living in water excluding amphibians, reptiles, mammals and birds. Section 3 of Chapter II prohibits the importation of several kinds of fish and other items listed in the section. Chapter III, inter alia, requires fish breeders to keep records on the purchase and sale of aquatic organisms. Section 11 provides for health certificates.