Determination of the optimum transfer time of kutum (Rutilus frisii kutum) larvae from live food to artificial dry feed Hossein Ouraji • Khosro Jani Khalili • Ghaffar Ebrahimi • Seyed Ali Jafarpour Received: 21 December 2009 / Accepted: 1 October 2010 / Published online: 20 October 2010 Ó Springer Science+Business Media B.V. 2010 Abstract Kutum Rutilus frisii kutum is known as a valuable commercial species in the southern part of Caspian Sea. Artificial rearing of fry has been introduced as an alternative to supply kutum fry in order to restock the kutum population in the Caspian Sea. The aim of this study was to find the suitable time to transfer kutum larvae from live food to artificial feed. The experiment began on day 3 post- hatching and lasted for 21 days. Mean initial weight of larvae was 4.5 mg. Five experimental groups including Group A (zoo- plankton alone for 21 days), Group B (12 days zooplankton ? 9 days artificial feed), Group C (8 days zooplankton ? 13 days artificial feed), Group D (4 days zooplank- ton ? 17 days artificial feed) and Group E (artificial feed alone for 21 days) were con- sidered for this experiment. According to the obtained results, the specific growth rate of kutum larvae varied from 8.01 to 13.58% day -1 , and the highest and lowest specific growth rate were found in A and E treatments, respectively. The lowest mean body weight (24.6 mg) was found in larvae fed on artificial feed for 21 days. However, survival rates of kutum larvae fed mixed zooplankton for 8 and 12 days (85.83 and 89.33%, respectively) were comparable with those of larvae fed live food during the entire experiment (91.6%). The lowest survival rate (69.16%) was found in larvae fed artificial feed during the entire experiment. Keywords Kutum Á Larvae Á Zooplankton Á Artificial feed Á Growth Introduction Kutum Rutilus frisii kutum (Kamenskii, 1901; family Cyprinidae) is an endemic fish of the Caspian Sea. It is a very valuable commercial species in Iran (Dorafshan and Heyrati 2006). This species is distributed in the Caspian Sea (Abdoli 1999). Considering more than 900 km of coastline in the southern part of Caspian Sea, kutum has a great economic H. Ouraji (&) Á K. J. Khalili Á G. Ebrahimi Á S. A. Jafarpour Department of Fisheries, Sari Agricultural Sciences and Natural Resources University, P.O.Box 578, Sari, Iran e-mail: hoseinoraji@yahoo.com 123 Aquacult Int (2011) 19:683–691 DOI 10.1007/s10499-010-9383-y