In most municipalities it's already illegal to release birds or mammals. From working as a volunteer with Huntsville (AL) Animal Services, if someone is suspected of releasing rabbits or cats an Animal Control officer will show up at their door and possibly arrest the perp. Fishes are seen in a different light; it's "just" a fish and it'll be fine in a local stream or pond, of course(!). What makes us weird on this list is thinking otherwise, and also being aware that such an introduction can have multiple bad effects. The effort to educate owners of mammalian pets about taking care of their charges and neutering them in most cases has taken decades, and is still ongoing (at least in the South...). We have a long way to go with the issue of releasing fish.
Georgia prohibits the release of any wildlife, wild animals, or domestic fish (except domestic fish can be released into private ponds). Of course I imagine it is very difficult to enforce these laws. Hope this helps!
§ 27-2-14. Liberation-of-wildlife and liberation-of-domestic fish permits
It shall be unlawful for any person to liberate any wildlife within this state or to liberate domestic fish except into private ponds except under permit from the department; provided, however, that pen raised quail may be released for purposes of training pointing, flushing, and retrieving dogs.
HISTORY: Ga. L. 1968, p. 497, § 20; Code 1933, § 45-315, enacted by Ga. L. 1977, p. 396, § 1; Ga. L. 1994, p. 600, § 2; Ga. L. 2002, p. 807, § 1; Ga. L. 2004, p. 948, § 2-3.
§ 27-5-7. Release or escape from captivity
It shall be unlawful for any person to release from captivity any wild animal as defined in paragraph (75) of Code Section 27-1-2 or to import, transport, sell, transfer, or possess such a wild animal in such a manner so as to cause its release or escape from captivity. In the event a person imports, transports, sells, transfers, or possesses a wild animal in such a manner so as to pose a reasonable possibility that such wild animal may be released accidentally or escape from captivity, the department may revoke the license or permit, or both, of such person pursuant to the procedure set forth in Code Section 27-2-25.
HISTORY: Code 1933, § 45-1104, enacted by Ga. L. 1977, p. 396, § 1; Ga. L. 1979, p. 1094, § 13; Ga. L. 1994, p. 1742, § 4.
§ 27-1-2. Definitions
As used in this title, the term:
(23) "Domestic species" means those taxa of animals which have traditionally lived in a state of dependence on and under the dominion and control of man and have been kept as tame pets, raised as livestock, or used for commercial breeding purposes, including, but not limited to, dogs, cats, horses, cattle, ratites, and chickens. Animals which live in a captive or tame state and which lack a genetic distinction from members of the same taxon living in the wild are presumptively wild animals, except that lawfully obtained farmed fish which are held in confinement in private ponds shall be known as and considered to be "domestic fish," but only if they are fish species which are either indigenous to Georgia or are fish species which have been recognized prior to 1992 as having an established population in Georgia waters other than private ponds; provided, however, that Morone americana, white perch, shall not be a domestic fish.
(75) "Wild animal" means any animal which is not wildlife and is not normally a domestic species in this state. This term specifically includes any hybrid or cross between any combination of a wild animal, wildlife, and a domestic animal. Offspring from all subsequent generations of such crosses or hybrids are wild animals.
(77) "Wildlife" means any vertebrate or invertebrate animal life indigenous to this state or any species introduced or specified by the board and includes fish, except domestic fish produced by aquaculturists registered under Code Section 27-4-255, mammals, birds, fish, amphibians, reptiles, crustaceans, and mollusks or any part thereof.
HISTORY: Left the history off on this one because it is so long.