They're legal to own as "aquarium pets" in Colorado. Getting a hold of one is the problem...
#012 POSSESSION OF AQUATIC WILDLIFE
A. Except as provided in these regulations or authorized by the Division of Wildlife or under Title
33 or Title 35 C.R.S., it shall be unlawful for any person to possess any live native or
nonnative aquatic wildlife in Colorado.
B. No person shall, at any time, have in possession or under their control any wildlife caught,
taken or killed outside of this state which were caught, taken or killed at a time, in a manner,
for a purpose, or in any other respect which is prohibited by the laws of the state, territory or
country in which the same were caught, taken or killed; or which were shipped out of said
state, territory or country in violation of the laws thereof.
C. Except as provided herein, the possession of the following species, their hybrids or viable
gametes is prohibited:
1. Bowfins: Amiidae.
2. Carp of the following genera: Aristichthys (including but not limited to bighead carp);
Catla (including but not limited to catla); Catlocarpio (including but not limited to giant
barb); Carrassius; Cirrhinus (including but not limited to mrigal); Cyprinus;
Hypophthalmichthys (including but not limited to silver carp and largescale silver carp);
Labeo (including but not limited to rohu; Mylopharyngodon (including but not limited to
black carp); and Tor (including but not limited to mahseers). However, grass carp and
common carp, including koi and goldfish may be possessed as otherwise provided for in
these regulations.
3. Catfish, Walking
4. Crayfish, Rusty
5. Eel, Asian Swamp
6. Frog, Green
7. Gars: Lepisosteidae - All species.
8. Gobies: Gobiidae.
9. Mussel, Quagga
10. Mussel, Zebra
11. New Zealand mudsnail
12. Perch, White
13. Piranha: Including members of the genera Serrasalmus and Pygocentrus.
14. Rudd
15. Ruffe, Eurasian
16. Snakeheads or murrels: Members of the genera Channa, Parachanna and Ophicephalus
17. Sticklebacks: Members of the genera Apeltes, Aulorhynchus, Gasterosteus and
Pungitius.
18. Tilapia: All species.
However, blue tilapia Mozambique tilapia Nile tilapia and their hybrids may be imported
and possessed for fish culture and educational purposes, provided the fish and their
progeny are held in facilities screened or otherwise designed to prevent their escape and
are not otherwise released into waters of the state. Screen mesh size shall be no larger
than 1/4" diameter. For the purposes of this regulation, fish culture means the raising of
fish for sale as food or for export, by a licensed aquaculturist, and educational purposes
means the raising of fish by educational facilities or for public display in public aquaria,
zoos, or other similar facilities.
19. Trahira
20. Water Fleas, Fish Hook and Spiny: Cercopagis pengoi, Bythotrephes lomgimanus, and
Daphnia lumholtzii.
Possession of the above species may be authorized as provided by Chapter 13 of these
regulations (Possession of Wildlife, Scientific Collecting and Special Licenses) or Title 35,
Article 80, C.R.S. (Pet Animal Care and Facilities Act), or as pets in private aquaria.
However, release of any of the above species into waters of the state is prohibited.