You have a Hypophthalmichthys nobilis (Bighead carp)
Species names: Hypophthalmichthys nobilis (Richardson, 1845)
Synonyms: Aristichthys nobilis, Leuciscus nobilis
Common names: Marmorkarpfen(AT), Marmorkarpfen(DE), Marmorkarpe(DK), kirju pakslaup (jämepea)(EE), raibais platpieris(LV), Grootkopkarper(NL), Marmorkarp(SE), tolstolobec pestrý(CZ), Margasis placiakaktis(LT), Tołpyga pstra(PL)
Dorsal spiness (total): 3; Dorsal soft rays (total): 7; Anal spines: 1-3; Anal soft rays: 12 - 14. Body with numerous scattered small black blotches. Keels extend from pelvic base to anus. Barbels absent. Posterior margin of last simple dorsal ray not serrated. Branched anal rays 13-14.5 (Kottelat et al. 1993). Differs from Hypophthalmichthys molitrix by having scaled keel from pelvic to anal, 240-300 long gill rakes, head length 27-35% SL, dark overall coloration, flank with dark, large, very irregularly shaped blotches, fin bases and inferior parts of head and belly yellowish (Kottelat and Freyhof, 2007).
For further information:
Similar Species: Hypophthalmichthys molitrix http://www.issg.org/database/species/SimilarSpecies.asp?si=773&fr=1&sts=&lang=EN
Native distribution: Hypophthalmichthys nobilis is reported to be native to central and south China
Introduced distribution: Introduced to numerous countries and has achieved a near globaldistribution
In its natural distribution range, Hypophthalmichthys nobilis inhabits rivers with marked water-level fluctuations. The species migrates long distances upriver at the beginning of a rapid flood and water-level increases (Huckstorf, 2012). Feed mostly on zooplankton, also algae (Huckstorf, 2012).
Reproduction: Hypophthalmichthys nobilis spawns for the first time at 5-6 years.
Spawns take place during floods, and in the upper water layer or even at water surfaces. Females spawn up to 1.1 million eggs in 1-3 portions depending on duration of high-water period. Eggs are yellowish, transparent, and hatch after about 2 days at temperatures around 25°C while drifting downstream in the deep open-water layer. If the eggs cannot drift long enough they fail to develop. After spawning, adults leave the river and migrate back to forage habitats. Larvae drift downstream and settle in floodplain lakes, shallow shores and backwaters with little or no current (Huckstorf, 2012).
Literature on Hypophthalmichthys nobilis
Kottelat, M. and J. Freyhof, 2007. Handbook of European freshwater fishes. Publications Kottelat, Cornol and Freyhof, Berlin, 646 pp.
Kottelat, M., A.J. Whitten, S.N. Kartikasari and S. Wirjoatmodjo, 1993. Freshwater fishes of Western Indonesia and Sulawesi = Ikan air tawar Indonesia Bagian Barat dan Sulawesi. Periplus Editions, Hong Kong. 293 p.
Huckstorf, V. 2012. Hypophthalmichthys nobilis. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 26 March 2015.