Feeding protocol for the Amazonian ornamental cichlid Apistogramma cacatuoides and a histological approach to the nutritional condition of larvae.

The aim of this study was to develop a feeding protocol for the larviculture of Apistogramma cacatuoides, using the histological approach to larval nutrition conditions. For this, three experiments were carried out. Experiment 1 was carried out in a randomized design to determine the optimal amount of Artemia nauplii (AN) per larva, and three treatments were evaluated: P1-feeding with 25 A. nauplii per larva (AN/L) during the first 5 days, followed by 50 AN/L from the 6th to the 10th day and 100 AN/L from the 11th to the 20th day; P2 and P3-37 and 50 AN/L during the first 5 days, 75 and 100 AN/L from the 6th to the 10th day and 150 and 200 AN/L from the 11th to the 20th day. Experiment 2 was carried out in a randomized design to determine the daily frequency of feeding and evaluated four feeding frequencies: F1-feeding only once a day (09:00); (F2)-feeding twice a day (09:00 and 17:00); F3-feeding three times a day (09:00, 11:30 and 17:00); and F4-feeding four times a day (09:00, 11: 30, 14:00 and 17:00). Experiment 3 lasted 40 days and was conducted in a randomized design to evaluate three periods for the beginning of the feeding transition: WE10:AN for 10 days, followed by 3 days of co-feeding and commercial feed until the end of the experimental period; WE15:AN for 15 days, followed by 3 days of co-feeding and commercial feed; WE20:AN for 20 days, followed by 3 days of co-feeding and commercial feed. The results of this study showed that, for the best development of the larvae, they should receive the feeding protocol 50-100-200 AN/L (P3) until the 20th day of exogenous feeding. From the 21st day, the transition to inert food should begin with 3 days of co-feeding, and feeding during larviculture should be carried out at a frequency of twice a day; this protocol provided a good nutritional status for the larvae, as shown by the histological approach.

Temperature-induced changes in reproductive variables in the teleost fish Lophiosilurus alexandri.

The present study evaluates whether increased water temperature induces reproduction by Lophiosilurus alexandri under controlled conditions, and investigates the effects of this procedure on sexual steroids, hematological profile and behavior. A 44-week experiment was performed with four wild males and 12 wild females that had been acclimatized to captive conditions. Water temperature was maintained at 24.4 ±â€¯1.0 °C for weeks 1-22, and then at 29.0 ±â€¯1.1 °C for weeks 22-44. Spawn weight, number of eggs/spawn and hatching rate were satisfactory and ranged 27.5-127.5 g, 1209-5183 and 83-89%, respectively. Hematocrit, leukocytes and glucose were not influenced by increased water temperature, while higher values for erythrocytes were observed for both sexes. The lowest value for plasma protein was for females maintained at 29.0 °C, while the lowest value for testosterone was obtained at the end of the study period at a temperature in 29.0 °C. Serum values of 17ß-estradiol were higher in females than in males, however, there was no evidence of variation as a function of experimental temperature or interaction with sex. The reproductive behavior of L. alexandri in captivity is described for the first time. The present study demonstrates that adult individuals are able to maintain a stable hematological profile during an increase in mean water temperature from 24.4 °C to 29.0 °C, even during the reproductive period, and still produce good quality larvae. Nonetheless, whether spawning was associated with increased 17ß-estradiol levels could not be determined.

Diferentes estratégias alimentares na larvicultura do acará-bandeira (Peterolophyllum scalare,Cichlidae) / Different feeding strategies on larval rearing of angelfish (Peterolophyllum scalare, Cichlidae)

The hatchery is one of the most critical stages of the development of fish and their success is directly related to food handling that can provide greater survival and growth. The aim of this study was to evaluate the time of dietary transition and providing meta-nauplii of Artemia spp. (MNA) for the angelfish larvae. Two experiments were conducted in a completely randomized design with five treatments and four repetitions. On each experiment there were used 540 fishes, distributed in 20 tanks with 2 liters each. In the first experiment, there were evaluated the dietary transition periods (MNA + Diet) for 1, 2, 3, 4 and 5 days. In the second experiment, there were evaluated the supply of MNA for 5, 10, 15, 20 and 25 days. There were evaluated: weight gain, growth rate and specific development, survival and batch uniformity (only in the experiment to evaluate the time of fish feed with MNA). There was no significant effect of different periods of dietary transition on the growth variables (p>0.05), but survival was higher (p<0.05) in the treatments composed of 3, 4 and 5 days of joint feed. In relation to the time of supply of MNA worse results were observed (p<0.05) when the time of supply of live food was shorter (5, 10 and 15 days). The animals were fed with MNA before feeding transition, for longer time (20 and 25) showed the best results for growth (p<0.05). Therefore, a food transition of three days and a supply of MNA for 20 days is recommended to perform the total replacement of live food for feed.

A larvicultura é uma das etapas mais críticas do desenvolvimento dos peixes e o seu sucesso está diretamente relacionado ao manejo alimentar, que pode proporcionar maiores sobrevivência e crescimento. Objetivou-se avaliar o tempo de transição alimentar e de fornecimento de meta-náuplios de Artemia spp (MNA) na larvicultura do acará-bandeira. Dois experimentos foram conduzidos em delineamento inteiramente casualizado com cinco tratamentos e quatro repetições. Em cada experimento foram utilizados 540 peixes distribuídos em 20 aquários com 2 L. No primeiro experimento, avaliaram-se os períodos de transição alimentar (MNA + ração) por 1, 2, 3, 4 e 5 dias. No segundo experimento, avaliou-se o período de fornecimento de MNA por 5, 10, 15, 20 e 25 dias. Foram avaliados: ganho de peso, taxas de crescimento e desenvolvimento específico, sobrevivência e uniformidade do lote (apenas no experimento para avaliar o tempo de fornecimento de MNA). Não houve efeito significativo dos diferentes períodos de transição alimentar sobre as variáveis de crescimento (p>0,05), porém a sobrevivência foi maior (p<0,05) nos tratamentos compostos por 3, 4 e 5 dias de alimentação conjunta. Em relação ao tempo de fornecimento de MNA, foram observados piores resultados (p<0,05) quando o tempo de fornecimento do alimento vivo foi menor (5, 10 e 15 dias). Os animais que foram alimentados com MNA antes da transição alimentar, por mais tempo (20 e 25 dias), apresentaram os melhores resultados de crescimento (p<0,05). Portanto, recomenda-se uma transição alimentar de três dias e um fornecimento de MNA por 20 dias para realizar a substituição total do alimento vivo pela ração.