Exploring the effects of eugenol, menthol, and lidocaine as anesthetics on zebrafish glucose homeostasis.

Zebrafish (Danio rerio) are widely employed as an experimental model in various scientific fields. The investigation of glucose metabolism dysfunctions has gained recent significant prominence. Considering that certain anesthetics may impact glycemic levels, it is imperative to carefully select an anesthetic that does not induce such side effects, thereby mitigating potential adverse influences on research outcomes. In this sense, this study aimed to evaluate potential glucose alterations and induction and recovery times resulting from the use of eugenol, menthol and lidocaine as anesthetics in zebrafish. A total of 150 adult male and female zebrafish were divided into ten groups, comprising a control group euthanized by rapid chilling, and three groups anesthetized with low (40 mg/L eugenol, 60 mg/L menthol, 100 mg/L lidocaine), intermediate (60 mg/L eugenol, 90 mg/L menthol, 225 mg/L lidocaine), and high (80 mg/L eugenol, 120 mg/L menthol, 350 mg/L lidocaine) anesthetic concentrations. Glucose levels and induction and recovery times were assessed. The findings reveal that eugenol and menthol did not cause glucose level alterations at any of the investigated concentrations, while lidocaine caused a non-concentration-dependent hyperglycemia. Eugenol and menthol also exhibited similar recovery times at different concentrations, while lidocaine recovery times were concentration-dependent. This study, therefore, concludes that eugenol and menthol are safe and satisfactory anesthetics for use in zebrafish research involving glucose analyses, while lidocaine use can cause biases due to altered glucose levels and safety concerns. Researchers should, therefore, carefully consider anesthetic selection to ensure reliable results in zebrafish assessments.

Effects of mixed feeding strategies with different dietary energy: protein ratios on juvenile Nile tilapia (Oreochromis niloticus) / Efeitos de estratégias de alimentação mista com diferentes relações de energia: proteína para juvenis de tilápia-do-Nilo (Oreochromis niloticus)

The evaluation of feeding strategies is necessary to ensure the sustainability of aquaculture. This study assessed the effect of two diets with different E:P ratios (9.6 and 10.3 kcal of digestible energy per gram of crude protein) on Nile tilapia juveniles. The growth, feed and nutrient use, economic parameters, whole-body composition, and liver steatosis of fish were evaluated. There was no significant effect of treatments on the growth, feed intake, feed conversion ratio, uniformity, and survival of the fish. The lower feed cost (P>0.05) per biomass or 1000 units produced was registered in Nile tilapia juveniles fed with 10.3 kcal DE/g CP diet for seven days. The contribution of ether extract in fish weight gain was reduced (P=0.055) by the increased use of the 10.3 kcal DE/g CP diet in the feeding strategies. The same trend was observed in fish whole-body lipid levels. Body indexes were similar (P>0.05) among fish from the different treatments. Mixing diets with different E:P ratios in a weekly feeding protocol does not impair productive performance of Nile tilapia juveniles. However, considering the cost of feeding, the recommendation is to supply a diet with 33%CPand 3.4 kcal/DE for seven days per week.(AU)

A avaliação das estratégias de alimentação é necessária para garantir a sustentabilidade da aquicultura. Este estudo avaliou o efeito de duas dietas com diferentes proporções de E:P (9,6 e 10,3 kcal de energia digestível por grama de proteína bruta) para juvenis de tilápia do Nilo. Foram avaliados o crescimento, uso da dieta e nutrientes, parâmetros econômicos, composição corporal e esteatose hepática de peixes. Não houve efeito significativo dos tratamentos sobre o crescimento, consumo de ração, conversão alimentar, uniformidade e sobrevivência dos peixes. O menor custo de ração (P>0,05) por biomassa ou 1000 unidades produzidas foi registrado nos juvenis de tilápia do Nilo alimentados com a dieta 10,3 kcal DE/g PB por sete dias. A contribuição do extrato etéreo no ganho de peso dos peixes foi reduzida (P=0,055) pela maior utilização da dieta 10,3 kcal DE/g PB nas estratégias de alimentação utilizadas. A mesma tendência foi observada nos níveis de lipídios corporais em peixes. Os índices corporais foram semelhantes (P>0,05) entre os peixes dos diferentes tratamentos. A mistura de dietas com diferentes relações E:P em um protocolo de alimentação semanal não prejudica o desempenho produtivo de juvenis de tilápia do Nilo. No entanto, considerando os custos de alimentação, a recomendação é fornecer uma dieta com 33% PB e 3,4 kcal/DE por sete dias por semana.(AU)

Dietary Brown Propolis Extract Modulated Nonspecific Immune System and Intestinal Morphology of Pacu Piaractus mesopotamicus

Abstract The immunomodulatory and growth promoter effects of brown propolis ethanolic extract (PEE) were determined in pacu. Fish (28.4±0.4 g) were randomly distributed into 12 polyethylene circular tanks (250 L, 30 fish per tank) and fed for 60 days with a commercial diet (32% crude protein) supplemented with 0.0, 1.5, 3.0 and 4.5% (v/w) of PEE in a totally randomized experimental design (n=3). Fish organic defense cells numbers such as thrombocytes and neutrophils increased (p<0.05) in fish fed 3.0% dietary PEE. Serum lysozyme concentration also increased (p<0.05) in fish fed 1.5 and 3.0% PEE supplementation when compared to unsupplemented fish. Growth parameters were not influenced (p>0.05) by treatments. Moreover, dietary PEE decreased (p<0.05) fish intestinal muscular thickness when compared to control treatment. Intestine villi height also significantly decreased in fish fed 3.0% PEE. Long term dietary PEE at 3.0% supplementation level modulated fish nonspecific immune system and it is a non-toxic substance for pacu.

Exposure of Nile Tilapia (Oreochromis niloticus) Fingerlings to a Saxitoxin-Producing Strain of Raphidiopsis (Cylindrospermopsis) raciborskii (Cyanobacterium) Reduces Growth Performance and Increases Mortality Rate.

Blooms of toxin-producing cyanobacteria have been more frequent and lasting because of the eutrophication of freshwater ecosystems, including those used for aquaculture. The aim of the present study was to investigate the effects of chronic exposure to a saxitoxin-producing strain of Raphidiopsis (Cylindrospermopsis) raciborskii on the performance of Nile tilapia (Oreochromis niloticus) fingerlings over a 60-d period. The fingerlings were cultivated under the following conditions: 1) water without cyanobacterium (WATER), 2) R. raciborskii in ASM-1 culture medium (CYANO), and 3) ASM-1 culture medium without cyanobacterium (ASM). Exposure to the CYANO treatment led to a significant increase in the mortality rate (p < 0.05) and a significant reduction in growth (p < 0.05) compared to fingerlings submitted to the ASM and WATER treatments, in which similar survival and growth were found (p > 0.05). Saxitoxin toxicity was dependent on the weight of the fingerling (p < 0.05), with maximum mortality caused by the ingestion of 13.66 µg saxitoxin equivalent L-1 g-1 . The present results clearly show the harm caused by saxitoxins to the production of Nile tilapia fingerlings in the early growth phase. These findings underscore the importance of maintaining adequate water quality in aquaculture activities to minimize the risk of saxitoxin-producing cyanobacterial blooms and avoid economic losses among producers. Environ Toxicol Chem 2020;39:1409-1420. © 2020 SETAC.

Heat-treated bean (Phaseolus vulgaris) residue meal as an alternative protein source in pelleted diets for Nile tilapia fingerlings: growth, body composition, and physical characteristics of diets.

The study aimed to evaluate heat-treated bean residue meal (Phaseolus vulgaris)-BRM-as an alternative protein source in diets for Nile tilapia fish. A completely randomized design was used, totaling four (n = 4) dietary treatments: diet without BRM (CON), raw BRM (RBRM) and heat-treated BRM at 100 °C for 15 min (BRM15), and 30 min (BRM30) before inclusion in diets. Nile tilapia fingerlings (1.3 g initial weight) were hand-fed the experimental diets for 66 days, divided equally into three meals per day. Performance parameters, body composition, nutrient retention, and physical characteristics of diets were evaluated. Growth and feed conversion were lower (P < 0.05) in fish fed BRM. Protein productive value was higher (P < 0.05) in fish fed CON diet than in fish receiving BRM. However, 30 min heat treatment of BRM increased (P < 0.05) protein retention in fish. Fish fed BRM30 also had higher protein content (P < 0.05) and reduced body lipid content (P < 0.05) than those fed CON diet. The physical characteristics (durability, dry matter leaching, waterproof time, and water stability time) were significantly improved (P < 0.05) in the BRM30 diet compared with other dietary treatments. The dietary inclusion of BRM at the level of 15% is not recommended for tilapia due to low growth performance and feed efficiency, regardless of preheating treatment. However, research on longer heat treatment time is needed due to the improvements observed in nutrient retention and physical characteristics of diets.

Substituição parcial do milho pelo resíduo de macarrão em dietas para tilápia-do-nilo / Partial replacement of corn by pasta waste in diets for Nile tilapia

A 50 days experiment was performed to evaluate the partial replacement of corn by pasta waste in Nile tilapia diets. Four isonitrogenous (30% crude protein) and isoenergetic (3,100 kcal kg-1 digestible energy) diets were formulated with increasing levels of corn replacement (0, 10, 20 and 30%) by pasta waste. Nile tilapia juveniles (11.2 ± 0.06 g) were distributed in 12 experimental cages (55 L) in six circular tanks of 310 L (2 cages per tank) in an indoor, recirculation system, under continuous aeration and emergency oxygenation system. Fish were fed to apparent satiation at 8:30 a.m. and 4:30 p.m. for 50 days, in a totally randomized experimental design (n = 3). Growth performance, protein and energy productive value and body composition of fish were evaluated. There were no significant differences in growth and body composition parameters between fish fed control and pasta residue diets. Replacement of 30% of dietary corn by pasta residue does not damage growth performance, protein and energy productive value and body composition of Nile tilapia juveniles.(AU)

Foi realizado um experimento de 50 dias para avaliar a substituição parcial do milho pelo resíduo de macarrão em dietas de tilápia-do-nilo. Foram formuladas quatro dietas isonitrogenadas (30% proteína bruta) e isoenergéticas (3.100 kcal kg-1 energia digestível) com níveis de substituição do milho pelo resíduo de macarrão (0, 10, 20 e 30%). Juvenis de tilápia-do-nilo (11,2 ± 0,06 g) foram distribuídos em 12 gaiolas experimentais (55 L) dispostas em seis tanques circulares de 310 L (2 gaiolas por tanque) em um sistema de recirculação de água, com aeração contínua e sistema de oxigenação emergencial. Os peixes foram alimentados até a aparente saciedade às 8:30 h e 16:30 h por 50 dias, em um delineamento inteiramente casualizado (n = 3). Foram avaliados: o desempenho produtivo, valor produtivo da proteína e energia e composição corporal dos peixes. Não foi observada diferença significativa no desempenho produtivo, retenção de proteína e composição corporal entre os peixes alimentados com a dieta controle (0%) e com resíduo de macarrão (10, 20 e 30%). A substituição de 30% do milho dietético pelo resíduo de macarrão não prejudica o desempenho produtivo, valor produtivo da proteína e energia e a composição corporal de juvenis de tilápia-do-nilo.(AU)

Substituição parcial do milho pelo resíduo de macarrão em dietas para tilápia-do-nilo / Partial replacement of corn by pasta waste in diets for Nile tilapia

A 50 days experiment was performed to evaluate the partial replacement of corn by pasta waste in Nile tilapia diets. Four isonitrogenous (30% crude protein) and isoenergetic (3,100 kcal kg-1 digestible energy) diets were formulated with increasing levels of corn replacement (0, 10, 20 and 30%) by pasta waste. Nile tilapia juveniles (11.2 ± 0.06 g) were distributed in 12 experimental cages (55 L) in six circular tanks of 310 L (2 cages per tank) in an indoor, recirculation system, under continuous aeration and emergency oxygenation system. Fish were fed to apparent satiation at 8:30 a.m. and 4:30 p.m. for 50 days, in a totally randomized experimental design (n = 3). Growth performance, protein and energy productive value and body composition of fish were evaluated. There were no significant differences in growth and body composition parameters between fish fed control and pasta residue diets. Replacement of 30% of dietary corn by pasta residue does not damage growth performance, protein and energy productive value and body composition of Nile tilapia juveniles.

Foi realizado um experimento de 50 dias para avaliar a substituição parcial do milho pelo resíduo de macarrão em dietas de tilápia-do-nilo. Foram formuladas quatro dietas isonitrogenadas (30% proteína bruta) e isoenergéticas (3.100 kcal kg-1 energia digestível) com níveis de substituição do milho pelo resíduo de macarrão (0, 10, 20 e 30%). Juvenis de tilápia-do-nilo (11,2 ± 0,06 g) foram distribuídos em 12 gaiolas experimentais (55 L) dispostas em seis tanques circulares de 310 L (2 gaiolas por tanque) em um sistema de recirculação de água, com aeração contínua e sistema de oxigenação emergencial. Os peixes foram alimentados até a aparente saciedade às 8:30 h e 16:30 h por 50 dias, em um delineamento inteiramente casualizado (n = 3). Foram avaliados: o desempenho produtivo, valor produtivo da proteína e energia e composição corporal dos peixes. Não foi observada diferença significativa no desempenho produtivo, retenção de proteína e composição corporal entre os peixes alimentados com a dieta controle (0%) e com resíduo de macarrão (10, 20 e 30%). A substituição de 30% do milho dietético pelo resíduo de macarrão não prejudica o desempenho produtivo, valor produtivo da proteína e energia e a composição corporal de juvenis de tilápia-do-nilo.

First report of albinism in trahira Hoplias malabaricus from Brazil / Primeiro registro de albinismo em traíra Hoplias malabaricus no Brasil

This paper is the first report on an adult female specimen of the trahira, Hoplias malabaricus, caught in the Pernambuco state, which exhibited the characteristics of total albinism.(AU)

Este trabalho é o primeiro registro sobre uma fêmea adulta de traíra, Hoplias malabaricus, capturada no estado de Pernambuco, que apresentou características de albinismo total.(AU)

First report of albinism in trahira Hoplias malabaricus from Brazil / Primeiro registro de albinismo em traíra Hoplias malabaricus no Brasil

This paper is the first report on an adult female specimen of the trahira, Hoplias malabaricus, caught in the Pernambuco state, which exhibited the characteristics of total albinism.(AU)

Este trabalho é o primeiro registro sobre uma fêmea adulta de traíra, Hoplias malabaricus, capturada no estado de Pernambuco, que apresentou características de albinismo total.(AU)