1. AKNOWLEDGMENTS This study was co-financed by the project “Innovations in finfish aquaculture with special references to reproduction” (acronym: InnovaFish), Operational Programme Sustainable Development of the Fisheries Sector and Coastal Fishing Areas 2007-2013" (OR14-61724-OR1400003/09/10/11). Presented at AQUA 2012 – Prague, 01-05 OCTOBER 2012 www.eng.InnovaFish.pl THE EFFECT OF DIET TYPE ON GROWTH AND SURVIVAL OF LARVAL BUENOS AIRES TETRA Hyphessobrycon anisitsi (Eigenmann, 1907). Krzysztof Kupren, Maja Prusinska, Slawomir Krejszeff, Dariusz Kucharczyk, Katarzyna Targonska, Daniel Zarski and Anna Hakuc-Blazowska Department of Lake and River Fisheries, University of Warmia and Mazury, Olsztyn, Poland Corresponding author: Krzysztof Kupren, University of Warmia and Mazury, ul. Warszawska 117a, 10-957 Olsztyn, Poland, phone: +48 (089) 524 56 02, e-mail: krzysztof.kupren@uwm.edu.pl References: Krejszeff, S., Żarski, D., Kucharczyk, D., Kupren, K., Targońska, K., Mamcarz, A. 2010. An experimental device for eggs incubation and fish larvae rearing under laboratory conditions. Polish Journal of Natural Sciences, 25(2), 190-199. Kupren K., Kucharczyk D., Prusińska M., Krejszeff S., Targońska K., Mamcarz A. 2008. The influence of shocking density on survival and growth of Buenos Aires tetra (Hemigrammus caudovittatus) larvae reared under controlled conditions. Polish Journal of Natural Sciences, 23(4): 881-887. Aquaculture is not only breeding fish for consumption but also breeding ornamental species (Kupren et al. 2008). Breeding of aquarium fish develops particularly dynamically in many countries around the world. Characidae living mainly in the tropical waters of South America are one of the groups of ornamental fish commonly bread worldwide. The best-known representatives of that group are Neon tetras. That group also includes other tetras, including the Buenos Aires tetra Hyphessobrycon anisitsi (Eigenmann, 1907) (Fig. 1). This is a small fish in captivity reaching ca. 7–9 cm in total length. In the natural environment it is most numerous in the La Plata basin. The aim of the study was to investigate the suitability of different kind of diet for Buenos Aires tetra larvae during their early feeding stage. The fish were reared for 25 days. Initially, during the first 15 days of the experiment, the larvae were fed on different diets: two sorts of Artemia nauplii, (groups a - Great Salt Lake Artemia Cysts, Artemia International LLC, b - San Francisco Origin Artemia Cysts, San Francisco Bay Brand, IN) decapsulated Artemia cysts (group c - INVE Artemia Schell Free, INVE Aquaculture Nutrition) and dry diet (group d). In the second phase of the experiment larvae were still fed on Artemia nauplii (groups a/a, b/a) and dry diet (group d/d). Additionally in two experimental groups Artemia nauplii were completely replaced with dry diet (groups a/d, b/d). The rearing of the larvae was carried out in a customized closed system consisting of one large glass 50 L tank functioning as a water bath with smaller 1 L tanks partially submerged in it (Krejszeff et al. 2011). The experiment started with exogenous feeding. Water temperature during the initial rearing was 26 o C. The larvae were fed ad libitum 3 times a day (8.00; 12.00 and 16.00). At the end of the first phase of the experiment, the larvae fed on Artemia nauplii, gained significantly higher length compared to the other groups (Fig. 2). The results obtained indicate also that after two weeks of rearing replaced of Artemia nauplii with dry diets has a small negative impact on the fish growth and survival (Tab. 2). Fig.2. Total Length of Buenos Aires tetra larvae measured on days 1, 5, 10 and 15 of the experiment (mean ± SD) Tab.1. Final characteristics of the rearing of Buenos Aires tetra (mean ± SD) Results in the same row with different letter indices differ significantly (P <0.05) Fig. 1. BUENOS AIRES TETRA source: http://www.mnf- fish.com/wp-content/uploads/buenos-aires-tetra.jpg