The introduction of Cichla ocellaris mainly occurs in altered environments, where the community of fishes is already in decline. The presence of these highly adapted and quickly proliferating predators causes serious damage to these communities by predation, competition, and cascade effects throughout the whole trophic chain (Gomiero and Braga, 2004). This species is a voracious piscivore capable of greatly modifying ecosystems where introduced. Some studies have reported as much as a 25% decline of forage fish from canals in which C. ocellaris have been introduced. There is speculation that if C. ocellaris continues to expand its range throughout southern Florida, faunas of less altered waters, such as those of the Everglades, could be at risk (Gulf States Marine Fisheries Commission, 2005).
However, other studies report beneficial effects of this species introudction into Florida's waterways such as attributed increases to native fish because C. ocellaris feeds on non-indigenous fish that have previously caused other native fish declines. Also, this species attracts recreational fishermen (Gomiero and Braga, 2004), which has accounted for a very large boon to the sport fishing industry in Florida. And some analyses and estimates reveal no major deleterious effects attributable to C. ocellaris, and indicate native fishes continue to exist satisfactorily with them (Shaflanda, 1999; and Shaflanda and Stanforda, 1999).
Location Specific Impacts:
Volta Grande Reservoir (Brazil)
Ecosystem change: Depending on its abundance levels, Cichla ocellaris causes varying degrees of modification in autochthonous fishes populations. , C. ocellaris is a typical piscivorous fish, with direct impact observable in secondary consumer populations. Indirectly, other trophic levels are affected: the fishes fed upon by the predator and, in turn, ichthyophagous birds, insects, and the zooplankton (Gomiero and Braga, 2004).
Reduction in native biodiversity: According to Godinho et al (1994), the richness of species in lakes following tucunaré and piranha introduction declined almost 50% in relation to what it had been and was smaller than that found on lakes without introductions (Gomiero and Braga, 2004).