# Management of the First Feeding of Dorada _Brycon sinensis_ with Two Species of Cladocerans
## 4 Discussion
In some species of fish studied, bioenergetic alterations are the result of varying prey size or density that is predominantly driven by foraging activity, and when the prey is large and/or more abundant, predators tend to be less active [44,45], which leads to less energy spent on hunting and more growth [43]. Stomach contents of dorada fed different cladocerans as live prey reflect higher consumption of _M. minuta_ (3.7 \(\pm\) 0.0 prey per stomach), followed by cladoceran mixture (3.4 \(\pm\) 0.1 prey per stomach), and finally by _M. elegans_ (1.1 \(\pm\) 0.1 prey per stomach). Notably, feeding with the mixture revealed greater food selectivity towards _M. minuta_ (2.6 \(\pm\) 0.0 prey per stomach) over _M. elegans_ (0.8 \(\pm\) 0.0 prey per stomach), suggesting the importance of the distribution and availability and movements of prey. Accordingly, _M. minuta_ presents desirable characteristics for the feeding of dorada larvae, such as size, shape, color, locomotion, and distribution. Among cladocerans, the genus _Moina_ is one of the most used in recent years for the first feeding of fish larvae. For example, the genus has been employed in the larvae of _Peterophyllum scalare_[46], _Sorubim cuspicaudus_[37], _Leiopotherapon plumbus_[47], _Orechromis niloticus_[48], and the crustacean _Macrobrachitium rosenbergii_[49] because it features many of the desired characteristics for feeding aquatic organisms, thereby ensuring larval growth [50]: adequate size, slow movement, high availability, appearance, chemical stimulation, minimum nutritional requirements, and easy ingestion. As previously described, the cladoceran _M. elegans_ was distributed near the walls, with short shifts near the surface of the walls of the experimental units. This natural behavior gives this genus of cladocerans low visibility for consumption by the dorada larvae. Therefore, its potential as prey for dorada larvae is limited by its natural habit of being associated with aquatic substrates [33,34]. This behavior is considered an adaptive strategy of some zooplankton organisms to prevent predation. [PERSON], et al. [5]) observed that in the stomach contents of hybrid catfish larvae (_Pseudoplatystoma corruscans x P. reticulatum_) kept in a previously fertilized pond, the food item _Macrothrix_ sp. (0.44%) was the least consumed live prey, attributed mainly to them being organisms typical of benthic regions that may be captured only by larvae that exhibit this benthic behavior. Therefore, _M. minuta_, presented with a homogeneous distribution in the water column, was a more visually attractive prey. [PERSON] [27] found a higher selection of cladocerans in the different items offered to larvae _Brycon amazonicus_. This preference was attributed to a set of morphological characteristics that confer greater visibility to the larvae (size, shape, and pigmentation), and associated with this. In addition, their interrupted movements were an important factor that influenced food selection by visual predators. [PERSON] [51] argued that size, shape, mobility, and contrast are the most important stimuli visual predators use in prey selection. In addition, the movement of the prey serves to differentiate the animate from the inanimate, which inclines the attention of the predator to a possible prey and increases the visibility of the same. On the other hand, [28] observed in larvae of _Piaractus mesopotamicus_ that the type of stimulus coming from _Artemia_ nauplii showed superior values of capture when they were compared with those stimuli coming from the inert diet; the authors indicated that the mobile prey induced tactile and visual responses and that the immobile prey escaped more easily from the attention of the predators. Dorada, as well as other bryconids, can be considered a visual predator [8,52, 53, 54] because its eyes are well developed and pigmented; it has a wide mouth armed with pointed teeth at the beginning of exogenous feeding, as observed during the present study. In particular, for _B.