Rearing of Procypris rabaudi during early life-history stages By W. N. Probst 1 , D. Tan 2 , Y. Gao 2 , A. Drossou 1 , C. Petereit 1 , B. Wecker 1 , M. Xiong 2 , B. Ueberscha¨r 1 , J. Chang 2 and H. Rosenthal 1 1 IFM-GEOMAR Leibniz-Institute of Marine Sciences, Kiel, Germany; 2 Institute of Hydrobiology, The Chinese Academy of Sciences, Luojiashan, Wuhan, China Summary The early life-history of Chinese rock carp Procypris rabaudi was investigated during a 56-day rearing period: 318 artificially propagated P. rabaudi larvae were reared throughout meta- morphosis in a small-scale recirculation system (345 L water volume, 10 · 18 L rearing tanks, 150 L storage and filter compartment with bioballs, 20–30 larvae L )1 ) at the Institute of Hydrobiology, Wuhan, Hubei Province, China. The newly hatched larvae had an initial total length of 8.93 ± 0.35 mm SD (n ¼ 10) at 3 days post-hatch and reached an average total length of 33.29 mm (±1.88 mm SD, n ¼ 10) 56 days after hatching. Length increment averaged 0.45 mm day )1 , resulting in a mean growth of 24.4 mm within the 56-day period. High mortality rates of up to 92% derived from an introduced fungus infection and subsequent treatment stress with malachite green. Our results indicate that Chinese rock carp can be raised successfully from artificially fertilized eggs. We therefore assume this species to be a candidate for commercial aquaculture. Introduction Chinese freshwater aquaculture has a long tradition in providing food fish for inland communities, and since the late-1970s the rapid development of Chinese aquaculture has been the focus of world attention (Guo, 2000; Hishamunda and Subasinghe, 2003). Within three decades the annual production was raised from 1.2 million tonnes (t) to 15.1 mil- lion t, reflecting an average annual growth rate of 16% (FAO, 2004). Between 1990 and 1995 Chinese aquaculture production increased by 7.5 million t. In 1997, almost 3 million people were employed in aquacultural enterprises (Song, 1999); as of 1996 aquacultural production exceeded Chinese commercial fisheries production. China’s aquaculture currently provides 54% of the world total aquaculture production and the total of utilized aquaculture areas has nearly doubled from 2.86 mil- lion ha in 1979 to 5.68 million ha in 1996 (Song, 1999; FAO, 2004). The most commonly farmed species comprise finfish of the order Cypriniformes, e.g. black carp (Mylopharyngodon piceus), grass carp (Ctenopharyngodon idella), silver carp (Hypophthalmichthys molitrix), bighead carp (Aristichthys nobilis), common carp (Cyprinus carpio), crucian carp (Caras- sius carassius), Chinese bream (Parabramis pekinensis), blunt- snout bream (Megalobrama amblycephala) and mandarin fish (Siniperca chuatsi; Song, 1999). However, as economical development has propagated the demand for high-valued food products, foreign fish species such as tilapia, rainbow trout, paddle fish, roach, river perch, toad catfish and salmonids have been introduced into Chinese aquaculture (Hishamunda and Subasinghe, 2003). The introduction of alien species (e.g. escapees from aquaculture sites) is considered to have substantial adverse effects on the native fauna (Rosenthal, 1980; Minchin and Rosenthal, 2002). Hence, it is considered advisable to give preference to native species when expanding aquaculture diversity (Perez et al., 2003). To promote the validity of native species for Chinese freshwater aquaculture, a cooperative effort between the European Union and China was launched in 1999 and entitled ECOCARP (funded by the European Commission, project number ICA4-CT-2001-2004). The major objectives of ECOCARP were not only to compile a list of native target species suitable for Chinese aquaculture, but also to evaluate their biological features in relation to (i) aquaculture production potential and (ii) restocking measures of endangered wild populations. Thus, ECOCARP aimed to contribute to the conservation of natural genetic resources and increase options for sustainable use of native aquatic resources. The selection of potential candidates focused on native species of the Yangtze River system where there is considerable potential for identifying new aquaculture species, since more than 370 indigenous fish species of the Yangtze River system are known (Duan et al., 2002; Park et al., 2003). However, only a few species have been tested for artificial breeding and further aquaculture purposes. Among the screened species, the Chinese rock carp Procy- pris rabaudi appears to be a promising candidate for aquaculture potential. Procypris rabaudi can reach 10 kg maximum body weight (BW) and grow up to 60 cm in length (J. Chang, unpubl. data), achieving market prices of 200– 300 Yuan kg )1 (20–30 € kg )1 ; Cai et al., 2003). However, in the past it appeared to be of minor importance to local fishing communities, considering the annual catches of <1 t [(Sichuan Yangtze Aquatic Resource Investigation Group, 1975; Duan et al., 2002); Surveys on commercial fisheries of the Institute of Hydrobiology, Wuhan (IHB)]. The stocking of commercially reared rock carp is derived from juvenile catches of wild populations. As a result, wild stocks have been in decline and the Chinese rock carp is now considered to be an endangered species (Yue and Chen, 1998; Duan et al., 2002; Park et al., 2003). Procypris rabaudi is distributed in branches of the upper Yangtze River, inhabiting deep-flowing waters of streams and rivers (Wu and Yang, 1979; Wang, 1998). Spawning occurs mainly between February and April, when sticky eggs attach J. Appl. Ichthyol. 22 (2006), 530–535 Ó 2006 Blackwell Verlag, Berlin ISSN 0175–8659 Received: May 27, 2005 Accepted: March 27, 2006 doi: 10.1111/j.1439-0426.2006.00817.x U.S. Copyright Clearance Centre Code Statement: 0175–8659/2006/2206–0530$15.00/0 www.blackwell-synergy.com