Topography of the Internal Organs of the Brown Bullhead (Ameiurus nebulosus) Lesueur, 1819 (Actinopterygii: Ictaluridae)

Abstract The problem of invasive species of fish is a major issue, both internationally and nationally. The presence of invasive species is often associated with acclimatization of new species of fish, activities correlated with the absence of effective control and quarantine programs. In other words, when new desired species are imported, other accompanying species are also brought in often in the form of embryonated eggs or juveniles.The brown bullhead, which we have studied, is also an invasive species of fish in Stejeris Lake, Cluj County. This species is of interest, both scientifically and economically. From the scientific point of view, brown bullhead has a high capacity of resistance to environmental changes, unfavourably conditions, which ensures a perpetuation of the species in almost every aquatic environment. Even though it is recognized that the economic impact of this invasive species is significant, not much information is available at present, and neither is there much data about the topography of its internal organs, which is being studied in this paper.