Abstract Among the different handling techniques in aquaculture, the use of anesthetics has had a growing interest focused on guaranteeing animal welfare, and reducing possible stress situations during general handling. The aim of this study was to present the use of eugenol and lidocaine with non-invasive anesthesia procedures in Dormitator latifrons, in which the different stages of anesthesia (induction and recovery) were determined. One hundred and twenty healthy fish of average weight of 73.59 ± 13.53 g and standard length of 17 ± 1.36 cm were used. The experimental fish were subjected to fasting for 24 h prior to the tests. Five fish were subjected to eugenol (25, 50, 100, and 200 µL/L), and lidocaine (100, 200, 300, and 400 mg/L), in triplicate. The time to reach deep and recovery anesthesia were recorded and the data analyzed using ANOVA (α= 0.05). Organisms exposed to anesthetics evidenced early episodes of fast, short-distance swimming (initial hyperactivity) for short periods of time. Survival was 100% with both compounds and concentrations. Fish exposed to a eugenol concentration of 200 µL/L had longer anesthesia times and took longer time to recover (P<0.05). The most effective concentrations for eugenol and lidocaine were of 200 µL/L and 400 µL/L in juvenile fish, promoting rapid inductions, without compromising the conditions for the recovery of the fish. This work provides practical information for handling and transportation D. latiforns with the least possible stress and ensuring animal welfare.

Resumo Dentre as diferentes técnicas de manejo na aquicultura, o uso de anestésicos tem despertado interesse crescente voltado para a garantia do bem-estar animal, reduzindo possíveis situações de estresse durante o manejo geral. O objetivo deste estudo foi apresentar o uso de eugenol e lidocaína com procedimentos anestésicos não invasivos em Dormitator latifrons, nos quais foram determinadas as diferentes etapas da anestesia (indução e recuperação). Foram utilizados 120 peixes saudáveis, com peso médio de 73,59 ± 13,53 g e 17 ± 1,36 cm de comprimento, em jejum de 24 horas antes dos testes. Cinco peixes foram submetidos a eugenol (25, 50, 100 e 200 µL/L) e lidocaína (100, 200, 300 e 400 mg/L), em triplicata. O tempo para atingir a anestesia profunda e de recuperação foi registrado, os dados foram analisados com ANOVA (α= 0,05). Organismos expostos a anestésicos evidenciaram episódios precoces de nado rápido de curta distância (hiperatividade inicial) por curtos períodos de tempo. A sobrevivência atinge 100% com ambos compostos e concentrações. Peixes expostos a uma concentração de eugenol de 200 µL/L tiveram tempos de anestesia mais longos e demoraram mais para se recuperar (P<0,05). As concentrações mais efetivas para eugenol e lidocaína foram de 200 µL/L e 400 µL/L em peixes juvenis, promovendo induções rápidas, sem comprometer as condições de recuperação dos peixes. Este trabalho fornece informações práticas para o manejo e transporte de D. latifrons com o mínimo de estresse possível e garantindo o bem-estar animal.

The effect of three diets with replacement of marine fish (20 and 40%) for beef liver in the growth and survival, and the effect of temperature on feed intake of young Crocodylus acutus was studied. Crocodiles fed the 40% of liver had the highest growth and 100% survival, with potential for greater tolerance to winter conditions.

Se estudió el efecto de tres dietas con sustitución de pescado marino (20 y 40%) por hígado de res en el crecimiento y supervivencia, así como el efecto de la temperatura en el consumo de alimento de crías de Crocodylus acutus. Los cocodrilos alimentados con la dieta de 40% de hígado tuvieron el mayor crecimiento y un 100% de supervivencia, con potencial de mayor tolerancia a condiciones invernales.

For aquaculture purposes, Macrobrachium íenellum is considered as a good candidate, is not aggressive nor presents cannibalism and can tolerate an ample interval of temperatures, salinities and oxygen concentrations. The present work evaluates the semi-intensive culture of M. íenellum under environmental conditions of summer and autumn with special attention to water temperature. The results of the experimental cultures in the tropical Mexican Pacific coast, suggest this species demonstrates better growth during the end of the spring, summer and the beginning of the autumn, time at which the average temperature of the water is near 30°C. The experimental cultures of end of autumn and beginnings of winter demonstrate minimum growth, with an average temperature of the culture water of 27°C. Other parameters like pH, O2 concentration and turbidity in the culture water were similar in all the experimental cultures reason why temperature is suggested the factor was the determinant in the differences found in growth.

Para fines de cultivo, Macrobrachium íenellum es considerado como un buen candidato pues no es agresivo ni presenta canibalismo, puede tolerar un amplio rango de temperaturas, salinidades y concentraciones de oxígeno. El presente trabajo evalúa el cultivo semiintensivo de M. íenellum bajo condiciones ambientales de verano y otoño con especial atención en la temperatura del agua. Los resultados de los cultivos experimentales en la costa tropical del Pacífico mexicano, sugieren que esta especie demuestra mejor crecimiento durante el final de la primavera, verano y principios del otoño, época en que la temperatura promedio del agua es cercana a 30°C. Mientras que los cultivos de finales de otoño e inicios de invierno demuestran crecimientos mínimos, con una temperatura promedio del agua de cultivo de 27°C. Otros parámetros físicoquímicos como pH, concentración de O2 y turbidez en el agua de cultivo fueron similares en todos los cultivos experimentales por lo que se sugiere que el factor temperatura fue el determinante en las diferencias encontradas en el crecimiento.