# Management of the First Feeding of Dorada _Brycon sinensis_ with Two Species of Cladocerans
## 1 Introduction  
Dorada _Brycon sinensis_ is an endemic species of fish of the Sinu River Basin (Cordoba, Colombia), threatened by the deterioration of its natural environment [1]. Like other bryconids, this species presents characteristics desirable for fish farming, including rapid growth, acceptance of artificial diets, easy adaptation to captivity, resistance to handling, and omnivorous diet [2]. The management of first feeding is done for only 24 h because this is the critical period of intensive larviculture of this species. This technique allows the larvae to be viable for the next stages of the production process and reduces cannibalism during this critical stage [2, 3]. The bryconids' life cycle is characterized by a fast embryonic stage (12-14 h to 26-28 \({}^{\circ}\)C); the larvae begin the exogenous feeding between 22 and 24 h after hatching (hae); management of first feeding is short (24 h). During this phase the maximum mouth opening is estimated at 20-25% of total length (5 to 6 mm); there is a short larval period (7 days); and like other bryconids, _Brycon sinensis_ shows strong cannibalism at the beginning of the exogenous feeding [2, 4, 5, 6, 7, 8]. This behavior causes low survival rates and heterogeneity in larval size [2, 7, 9]. To reduce cannibalism in bryconids, larvae of another fish species (forage larvae) are often supplied as an initial live feed to increase survival and control cannibal behavior in this stage of larviculture. The rearing of fingerlings of dorada has advanced in the use of forage larvae with the first feeding management [2]; however, this method increases the production costs of fingerlings, so it isnecessary to look for alternatives with zootechnical potential as an initial live food source for the production of fingerlings without the use of forage larvae. A possible alternative for managing bryconids' first feeding and cannibalism control is the use of cladocerans selected and grown under controlled conditions. The potential of cladocerans as a biotech food alternative for the performance of fish of aquaculture interest is well known. During rearing, dorada culture (nearly 15 days) shows selectivity for zooplankton groups, copepods, and ostracods [10]. Still, no studies evaluated the use of cladocerans in the first feeding of dorada larvae. The biochemical composition of cladocerans is important for fish larvae because it contains most of the nutritional requirements for the survival and adequate development of the larvae [11; 12]. Furthermore, due to their content of essential fatty acids [13; 14; 15; 16; 17] and high levels of excellent quality protein [18], cladocerans are an essential source of the vitamins, minerals [19], and enzymes necessary for larval growth and survival [20; 21; 22]. Most fish larvae require planktonic organisms as their first feed and record better growth and survival rates when fed these organisms rather than artificial diets [5; 10; 23; 24; 25; 26]. Several factors explain these results: the structure and digestibility of the protein, presence of exogenous enzymes, chemical stimuli, adequate size, and slow movements of the prey that facilitate its ingestion and digestion, characteristics that meet the requirements of the larva [27]. Another feature that justifies the use of cladocerans in fish larviculture is the predatory visual stimulus provided to larvae due to the natural motility of the plankton [28]. Despite the lack of information on the management of the first feeding of _B. sinensis_ with selected cladocerans, the described characteristics make this zooplankton an interesting option to be evaluated as prey in larviculture. As stated in the 2021 Shanghai Declaration: Aquaculture for food and sustainable development, diversification is presented as an option or key to sustainable development. The diversification of aquaculture production implies new investment alternatives for both the industrial and artisanal sectors, and the first step is to expand the variety of species offered by aquaculture.