Feeding of larvae of the hybrid surubim Pseudoplatystoma sp. under two conditions of food management

Abstract

ABSTRACT. We evaluated the growth and diet composition of hybrid surubim larvae (Pseudoplatystoma corruscans x P. reticulatum) produced in two fish farming by using different systems of feeding with natural plankton: M I, larvae are transferred to fertilized fish pond for being freely fed with natural plankton; M II, larvae are remained inside laboratory in glass fiber boxes and plankton are gathered with a plankton net and offered in a controlled way. It was collected 10 individuals daily during the feeding period with live plankton for 20 days. After the biometry, stomachs were opened and the food items identified and quantified by the volumetric method. The items were represented by algae, protozoa, microcrustacean, insect larvae and surubim fragments (cannibalism). The items with higher volumetric percentage were Chironomidae larvae (29.25%) followed by surubim fragments (19.68%) in M I, and surubim fragments (21.85%) and Moina micrura (19.97%) in MII. The items Chydorus sp., Diaphanosoma sp., sp. Macrothrix and Ephemeroptera larvae were found only in fish of M I, while algae Ulothrix sp., Oscillatoria sp. and the protozoa Difflugia sp were only found in stomachs of surubim from M II. Regarding the growth, the surubim had grown faster in M I.Keywords: larviculture, freshwater fish, diet.Alimentação de larvas do surubim híbrido Pseudoplatystoma sp. sob duas condições de manejo alimentar RESUMO. Este trabalho avaliou o crescimento e a composição da dieta de larvas do surubim híbrido (Pseudoplatystoma corruscans x P. reticulatum) produzidas em duas pisciculturas que utilizam sistemas diferentes de alimentação com plâncton natural: M I, as larvas são transferidas para viveiros previamente fertilizados para se alimentarem livremente com plâncton natural e M II, as larvas permanecem no laboratório em caixas de fibra de vidro e o plâncton são coletados com rede e oferecidos de forma controlada. Foram coletados dez exemplares por dia durante 20 dias. Após a biometria e a retirada dos estômagos, os itens alimentares foram identificados e quantificados por meio do método volumétrico. Os itens com maiores percentuais volumétricos foram larvas de Chironomidae (29,25%) seguido de restos de surubim (19,68%) em M I e restos de surubim (21,85%) e Moina micrura (19,97%) em M II. Os itens Chidorus sp., Diaphanosoma sp., Macrotrix SP. e larvas de Ephemeroptera foram encontrados apenas nos estômagos dos surubins do M I, enquanto as algas Ulothrix sp., Oscillatoria sp., assim como o protozoário do gênero Diflugia, foram observados apenas nos estômagos dos surubins do M II. Em relação ao crescimento, os surubins do M I apresentaram crescimento mais rápido do que em M II.Palavras-chave: larvicultura, peixe de água doce, dieta.

Management of the First Feeding of Dorada Brycon sinuensis with Two Species of Cladocerans

“…This behavior is considered an adaptive strategy of some zooplankton organisms to prevent predation. da Silva, 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.…”

“…The bryconids' life cycle is characterized by a fast embryonic stage (12-14 h to 26-28 • 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 sinuensis 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].…”

“…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].…”

Development, nutrition, and rearing practices of relevant catfish species (Siluriformes) at early stages

“…and interspecific hybrids are reared similarly. Larvae are fed Artemia nauplii during the first 7–10 days until they develop skin pigmentation 122,123 . Feeding ratios consist of 500 Artemia nauplii per larva per day during the first 5 days, and 1000 nauplii per larva per day from day 6 to 10, divided into 6 to 10 rations distributed along 24 h 26,122 .…”

“…After this initial period when body pigmentation is developed, larvae can be reared indistinctly in tanks connected to a recirculating system or in outdoor fertilised ponds, a choice that depends on available facilities (Table 5). 26,122,123 …”