The Colorado Department of Natural Resources, Division of Wildlife website has some information regarding prohibited aquatic species:http://wildlife.state.co.us/RulesRegs/Spec...icenses/FAQ.htm
According to the Colorado DNR regulations, Article VII, #012, subsection C, possession of the following aquatic species, their hybrids or viable gametes is prohibited, unless authorized by DNR as pets in private aquaria:
1. Bowfins: Amiidae
2. Carp, Big Head: Aristichthys nobilis
3. Carp, Black: Mylopharyngodon piceus.
4. Carp, Hybrid Grass: Ctenopharyngodon idella X Aristichthys nobilis.
5. Carp, Indian: Catla (Catla catla), rohu (Labeo rohita), mrigal (Cirrhinus mrigala).
6. Carp, Silver: Hypopthalmichthys molitrix.
7. Catfish, Walking: Clarias batrachus.
8. Crayfish, Rusty: Orconectest rusticus.
9. Eel, Asian Swamp: Monopterus albus.
10. Frog, Green: Rana clamitans.
11. Gars: Lepistosteidae -- All species.
12. Gobies: Gobiidae.
13. Mussel, Quagga: Dreissena bugensis.
14. Mussel, Zebra: Dreissena polymorpha.
15. New Zealand mudsnail: Potamopyrgus antipodarum.
16. Perch, White: Morone americana.
17. Piranha: Including members of the genera Serrasalmus and Pygocentrus.
18. Rudd: Scardinius erythropthalmus.
19. Ruffe, Eurasian: Gymnocephalus cernuus.
20. Snakeheads or murrels: Members of the genera Channa, Parachanna and Ophiocephalus.
21. Sticklebacks: Members of the genera Apeltes, Aulorhynchus, Gasterosteus and Pungitus.
22. Tilapia: All species. However, blue tilapia (Oreochromis aurea), Mozambique tilapia (Oreochromis mossambica), Nile tilapia (Tilapia nilotica), 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 aquaculturalist, and "educational purposes" means the raising of fish by educational facilities or for public display in public aquaria, zoos, or other similar facilities.
23. Trahira: Hoplias malabaricus.
24. Water Fleas, Fish Hook and Spiny: Cercpagis pengoi, Bythotrephes lomgimanus, and Daphnia lumholtzii.