First report of thyroid goiter in the marine ornamental fish Gramma brasiliensis.

Enlargement of the thyroid gland is referred to as goiter. In captive fish, goiter may be associated with iodine deficiency in water or diet, exposure to goitrogenic factors such as a high environmental nitrate concentration or water treatment with ozone. This report describes the occurrence of goiter in a marine ornamental fish raised in a research laboratory, the Brazilian basslet Gramma brasiliensis. From 2016 to 2023, we observed progressively growing tumour-like masses in the pharyngeal cavity and along the gill arches of approximately 20 adult individuals. This abnormal growth impaired the ingestion of food and caused dyspnoea, leading the animals to death within a few months after the first appearance of the mass. The samples were submitted to histological analyses, which revealed moderate to severe, diffuse, hypertrophy and hyperplasia of thyroid follicular cells with most lacking colloids. This is the first report of goiter in the Brazilian basslet. Although it is not clear why this condition develops in this species, we recommend keeping nitrate levels to a minimum and monitoring water iodine concentrations regularly until future studies investigate the possible causes and adequate treatment for this species.

O aumento da glândula tireóide é conhecido como bócio. Em peixes em cativeiro, o bócio pode estar associado à deficiência de iodo na água ou na dieta, à exposição a fatores goitrogênicos, como alta concentração de nitrato ou ao tratamento da água com ozônio. O presente relato descreve a ocorrência de bócio em um peixe ornamental marinho criado em laboratório de pesquisa, o Gramma brasiliensis. De 2016 a 2023, observamos crescimento progressivo de massas semelhantes a tumores na cavidade faríngea e ao longo dos arcos branquiais de aproximadamente 20 indivíduos adultos. Esse crescimento anormal prejudicou a ingestão de alimentos e causou dispneia, levando os animais à morte em poucos meses, desde o início do aparecimento das massas. As amostras foram submetidas à análise histológica, evidenciando hipertrofia e hiperplasia moderada a grave, difusa, de células foliculares tireoidianas, sendo a maioria delas desprovida de colóide. Este é o primeiro relato de bócio em grama brasileiro. Apesar da razão pouco clara para o desenvolvimento desta condição nesta espécie, recomendamos manter os níveis de nitrato ao mínimo e monitorar regularmente as concentrações de iodo na água até que próximos estudos investiguem as possíveis causas e o tratamento adequado para esta espécie.

Tank color influences the response of tomato clownfish (Amphiprion frenatus) to an acute stress challenge.

The trade of aquarium organisms is growing worldwide. This market depends on a continuous supply of healthy and colorful aquatic animals, but this sector has few initiatives. However, in the last decade, there has been a growing interest in researching captive breeding of these animals, aiming to develop a more sustainable aquarium hobby. Larviculture is an important phase in the cultivation process because the larvae are more sensitive to stress and variations in the bulk of variables, such as temperature, salinity, nutritional management, light intensity and spectrum, and environmental background colors. Because background color could be a promoter variable of proper welfare, we tested whether it affects the endocrine response of tomato clownfish Amphiprion frenatus larvae to an acute stress challenge. We show that background color influences the endocrine stress axis responsiveness in tomato clownfish. When fish were subjected to a standard acute stressor of 61 days after hatching, only fish adapted to white walls increased the whole-body cortisol levels. From the results presented herein, we recommend that white tanks be avoided for A. frenatus larviculture. Both, the less stress level and the good welfare condition of larvae reared in colored tanks may have robust, practical applications since almost all clownfish in the ornamental aquarium trade come from captive breeding.

Spawning, egg and larval description of the brazilian basslet Gramma brasiliensis Sazima, Gasparini & Moura, 1998 in captivity.

Brazilian basslet Gramma brasiliensis is a fish highly appreciated by the marine ornamental industry. There is an increasing interest in the development of a breeding protocol for this species. However, descriptions of the reproductive biology, eggs and larval development are scarce. This study was the first to describe the spawning, eggs and larvae of G. brasiliensis in captivity, including mouth size information. Six spawning events produced egg masses with 27, 127, 600, 750, 850, and 950 eggs. Larger egg masses showed embryos with at least two different developmental stages. Eggs are spherical (∼1.0 mm diameter), held together by filaments entangling chorionic projections. Larvae with fewer than 12 hph (hours post-hatch) presented 3.55 mm standard-length, well developed eyes, fully absorbed yolk sac, an inflated swim bladder and mouth opened. Exogenous feeding on rotifers began within 12 hph. The average mouth width at first feeding was 0.38 mm. The first settled larva was noted by day 21. This information should help to determine appropriate diets and prey-shift time during the larviculture of the species.

Embryonic and early larval development of two marine angelfish, Centropyge bicolor and Centropyge bispinosa.

Marine angelfish (family: Pomacanthidae) are among the most sought-after fish species in the saltwater aquarium trade. However, there is a lack of information in the literature on their early ontogeny. The objective of this study was to describe the embryonic and early larval development of two dwarf angelfish, the bicolour angelfish, Centropyge bicolor and the coral beauty angelfish, Centropyge bispinosa. The eggs of these two species were obtained from spontaneous spawning of the broodstock fish in captivity and incubated at 26.0 ± 0.2°C throughout the study. Fertilized eggs (n = 15) of both species are transparent, pelagic and spherical; the mean diameters of the eggs were measured at 703.6 ± 7.8 µm for C. bicolor and 627.6 ± 7.8 µm for C. bispinosa. The eggs of both species possessed a narrow perivitelline space, smooth and thin chorion, a homogenous and non-segmented yolk as well as a single oil globule. Overall, the observed embryonic development pattern of C. bicolor and C. bispinosa was very similar, and the main difference was the embryonic pigmentation pattern, which only became evident close to hatching. Larvae of both species started hatching at 13 h 30 min after fertilization, and the larval characteristics of both species also showed high levels of similarities. However, the mouth opening time for C. bicolor was 72 h after hatching (AH) and 96 AH for C. bispinosa. In general, the observed early ontogeny of C. bicolor and C. bispinosa also resembled that of other Centropyge species documented in the literature.

Thermal influence on the embryonic development and hatching rate of the flameback pygmy angelfish Centropyge aurantonotus eggs.

The flameback pygmy angelfish Centropyge aurantonotus, highly appreciated and valued by the aquarium market, is heavily harvested and traded. Temperature is one of the abiotic factors that has the most influence on fish development, especially in the early stages of life. For captive production, it is essential to know the appropriate environmental parameters for each species. In this sense, this study aimed to evaluate the influence of temperature on the embryonic development and hatching rates of C. aurantonotus incubated at six different temperatures (20, 22, 24, 26, 28, 30°C). Embryonic development events were very similar in terms of morphological and chronological characteristics compared with other species of the genus Centropyge. Incubation time was inversely proportional to temperature. The treatment at 22°C required twice the time of that required by 30°C treatment for hatching to occur. The best incubation temperature range was 24-28°C. Values below 22°C and at 30°C showed lower hatching rates compared with other treatments. Based on these results, the recommended temperature at which to incubate C. aurantonotus eggs is between 24-28°C.

Development and health status of Centropomus undecimalisparasitized by Rhabdosynochus rhabdosynochus (Monogenea) under different salinity and temperature conditions.

This study evaluated the correlation of hematological parameters with the mean abundance of the monogenean helminth Rhabdosynochus rhabdosynochus in Centropomus undecimalis reared at different temperatures and salinities. The experimental conditions were: 28 °C/0 ppt (parts per thousand); 28 °C/15 ppt; 28 °C/32 ppt; 25 °C/0 ppt; 25 °C/15 ppt; and 25 °C/32 ppt. The prevalence was 100.0% in fish at 28 °C/15 ppt, 28 °C/32 ppt and 25 °C/15 ppt, which was significantly different (p < 0.05) from those at 25 °C/32 ppt. The red blood cell (RBC) count, hematocrit and total leukocyte (WBC) count were significantly higher in fish at 28 °C/15 ppt and 28 °C/32 ppt. The mean abundance of R. rhabdosynochus, hematocrit and RBC showed positive correlations (P < 0.05) with temperature (ρ= 0.3908; ρ= 0.4771 and ρ = 0.2812). Mean abundance showed negative correlations with hemoglobin (ρ= -0.3567) and mean corpuscular hemoglobin concentration (MCHC) (ρ = -0.2684). No correlation between abundance and salinity was detected among the experimental conditions (ρ = -0.0204). The low numbers of monogeneans recorded (min -1 and max -33) explain the few changes to fish health. This suggests that these experimental conditions may be recommended for development of rearing of C. undecimalis in Brazil, without any influence or economic losses from R. rhabdosynochus.

Development and health status of Centropomus undecimalisparasitized by Rhabdosynochus rhabdosynochus (Monogenea) under different salinity and temperature conditions / Desenvolvimento e estado de saúde de Centropomus undecimalisparasitado por Rhabdosynochus rhabdosynochus (Monogenea) sob diferentes condições de salinidade e temperatura

This study evaluated the correlation of hematological parameters with the mean abundance of the monogenean helminth Rhabdosynochus rhabdosynochus in Centropomus undecimalis reared at different temperatures and salinities. The experimental conditions were: 28 °C/0 ppt (parts per thousand); 28 °C/15 ppt; 28 °C/32 ppt; 25 °C/0 ppt; 25 °C/15 ppt; and 25 °C/32 ppt. The prevalence was 100.0% in fish at 28 °C/15 ppt, 28 °C/32 ppt and 25 °C/15 ppt, which was significantly different (p < 0.05) from those at 25 °C/32 ppt. The red blood cell (RBC) count, hematocrit and total leukocyte (WBC) count were significantly higher in fish at 28 °C/15 ppt and 28 °C/32 ppt. The mean abundance of R. rhabdosynochus, hematocrit and RBC showed positive correlations (P < 0.05) with temperature (ρ= 0.3908; ρ= 0.4771 and ρ = 0.2812). Mean abundance showed negative correlations with hemoglobin (ρ= -0.3567) and mean corpuscular hemoglobin concentration (MCHC) (ρ = -0.2684). No correlation between abundance and salinity was detected among the experimental conditions (ρ = -0.0204). The low numbers of monogeneans recorded (min -1 and max -33) explain the few changes to fish health. This suggests that these experimental conditions may be recommended for development of rearing of C. undecimalis in Brazil, without any influence or economic losses from R. rhabdosynochus.

Este estudo avaliou a correlação dos parâmetros hematológicos com a abundância média de helmintos monogenea Rhabdosynochus rhabdosynochus em robalo-flecha, Centropomus undecimalis, cultivado em diferentes temperaturas e salinidades. As condições experimentais foram: 28 °C/0 ‰; 28 °C/15 ‰; 28 °C/32 ‰; 25 °C/0 ‰; 25 °C/15 ‰; 25 °C/32 ‰. A prevalência (P) foi de 100,0% nos peixes de 28 °C/15 ‰, 28 °C/32 ‰, 25 °C/15 ‰ significativamente diferente (p<0,05) dos peixes de 25 °C/32 ‰ (P=75,0%). O número de eritrócitos, hematócrito e leucócitos totais foram significativamente maiores nos peixes mantidos a 28 °C/15 ‰ e 28 °C/32 ‰. A abundância média de R. rhabdosynochus, hematócrito e número de eritrócitos mostraram correlação positiva (p<0,05) com a temperatura (ρ = 0,3908; ρ = 0,4771 e ρ = 0,2812, respectivamente). Houve correlação negativa da abundância média com a hemoglobina (ρ = -0,3567) e a concentração de hemoglobina corpuscular média (CHCM) (ρ = -0,2684). Não houve correlação entre a abundância e a salinidade entre os tratamentos (ρ = -0,0204). O baixo número de Monogenea registrado (mín: 1 e máx: 33) justifica as poucas alterações na saúde dos animais avaliados. Isso sugere que essas condições experimentais de cultivo podem ser recomendadas para um futuro desenvolvimento do cultivo de C. undecimalis no Brasil, sem que haja influência e perdas econômicas associadas a mortalidades, por parasitos R. rhabdosynochus.

Feeding frequency affects growth of juvenile cobia Rachycentron canadum cultured in near-shore cages / Efeito da frequência alimentar no crescimento de juvenis de bijupirá Rachycentron canadum criados em tanques tipo near-shore

Growth performance of juvenile cobia Rachycentron canadum (15.7 ± 0.4 g; mean ± SD) reared in 1 m3 near-shore cages, 24.0 ± 2.1 ºC, fed a Brazillian commercial feed (45% crude protein and 16% lipid) until apparent satiation, in a single feeding (F1), two (F2) or three (F3) feedings per day, for 30 days was assessed. The initial stocking density was 0.6 kg m-3. Production performance of juvenile cobia was significantly affected by feeding frequency. Groups fed two and three equal feedings per day presented greater and more efficient growth than F1 groups. There was no difference between F2 and F3 treatments for weight gain (15.6 ± 1.5 g and 16.3 ± 2.0 g, respectively), specific growth rate (SGR: 2.3 ± 0.3% and 2.5 ± 0.4% of body weight per day, respectively) and feed conversion ratio (FCR: 2.3 ± 0.2 and 2.5 ± 0.3, respectively). However, these parameters were reduced in F1 treatment (weight gain of 8.4 ± 1.1 g; SGR = 1.4 ± 0.2% and FCR = 3.2 ± 0.6) (P 0.05). The coefficient of variation was inversely proportional to the increase in feeding frequency. There was no significant difference in terms of survival rates, being superior to 90% in all treatments. We suggestthat growth performance of juvenile cobia cultured in near-shore cages can be optimized at a feeding frequency of two times a day, facilitating husbandry procedures and minimizing costs related to labor and vessel utilization.(AU)

O desempenho de juvenis de bijupirá Rachycentron canadum (15,7 ± 0,4 g; média ± DP) criados em tanques-rede de 1 m³, em uma baía protegida, 24,0 ± 2,1 C, alimentados com uma ração comercial brasileira (45% de proteína bruta e 16% de gordura) até saciedade aparente, alimentados em uma (F1), duas (F2) e três (F3) refeições por dia, durante 30 dias, foi avaliado. A densidade de estocagem inicial foi de 0,6 kg m-3. O desempenho de produção de juvenis de bijupirá foi afetado significativamente pela frequência alimentar. Grupos alimentados duas e três vezes ao dia apresentaram um crescimento maior e mais eficiente do que os grupos F1. Não houve diferença entre os tratamentos F2 e F3 para o ganho em peso (15,6 ± 1,5 g e 16,3 ± 2,0 g, respectivamente), taxa de crescimento específica (TCE: 2,3 ± 0,3% e 2,5 ± 0,4% do peso corporal diário, respectivamente) e conversão alimentar aparente (CAA: 2,3 ± 0,2 e 2,5 ± 0,3, respectivamente). No entanto, os tratamentos F2 e F3 promoveram melhores resultados comparados ao tratamento F1 (ganho em peso: 8,4 ± 1,1 g; TCE = 1,4 ± 0,2%; CAA = 3,2 ± 0,6) (p 0,05). O coeficiente de variação foi inversamente proporcional ao aumento da frequência alimentar. Não houve diferença significativa para taxa de sobrevivência, sendo superior a 90% em todos os tratamentos. Este trabalho sugereque o desempenho do crescimento de juvenis de bijupirá criados em condições do presente estudo pode ser otimizado quando alimentados duas vezes ao dia, facilitando os procedimentos de criaçãoe minimizando os custos relacionados com mão-de-obra e embarcação.(AU)

Feeding frequency affects growth of juvenile cobia Rachycentron canadum cultured in near-shore cages / Efeito da frequência alimentar no crescimento de juvenis de bijupirá Rachycentron canadum criados em tanques tipo near-shore

Growth performance of juvenile cobia Rachycentron canadum (15.7 ± 0.4 g; mean ± SD) reared in 1 m3 near-shore cages, 24.0 ± 2.1 ºC, fed a Brazillian commercial feed (45% crude protein and 16% lipid) until apparent satiation, in a single feeding (F1), two (F2) or three (F3) feedings per day, for 30 days was assessed. The initial stocking density was 0.6 kg m-3. Production performance of juvenile cobia was significantly affected by feeding frequency. Groups fed two and three equal feedings per day presented greater and more efficient growth than F1 groups. There was no difference between F2 and F3 treatments for weight gain (15.6 ± 1.5 g and 16.3 ± 2.0 g, respectively), specific growth rate (SGR: 2.3 ± 0.3% and 2.5 ± 0.4% of body weight per day, respectively) and feed conversion ratio (FCR: 2.3 ± 0.2 and 2.5 ± 0.3, respectively). However, these parameters were reduced in F1 treatment (weight gain of 8.4 ± 1.1 g; SGR = 1.4 ± 0.2% and FCR = 3.2 ± 0.6) (P 0.05). The coefficient of variation was inversely proportional to the increase in feeding frequency. There was no significant difference in terms of survival rates, being superior to 90% in all treatments. We suggestthat growth performance of juvenile cobia cultured in near-shore cages can be optimized at a feeding frequency of two times a day, facilitating husbandry procedures and minimizing costs related to labor and vessel utilization.

O desempenho de juvenis de bijupirá Rachycentron canadum (15,7 ± 0,4 g; média ± DP) criados em tanques-rede de 1 m³, em uma baía protegida, 24,0 ± 2,1 C, alimentados com uma ração comercial brasileira (45% de proteína bruta e 16% de gordura) até saciedade aparente, alimentados em uma (F1), duas (F2) e três (F3) refeições por dia, durante 30 dias, foi avaliado. A densidade de estocagem inicial foi de 0,6 kg m-3. O desempenho de produção de juvenis de bijupirá foi afetado significativamente pela frequência alimentar. Grupos alimentados duas e três vezes ao dia apresentaram um crescimento maior e mais eficiente do que os grupos F1. Não houve diferença entre os tratamentos F2 e F3 para o ganho em peso (15,6 ± 1,5 g e 16,3 ± 2,0 g, respectivamente), taxa de crescimento específica (TCE: 2,3 ± 0,3% e 2,5 ± 0,4% do peso corporal diário, respectivamente) e conversão alimentar aparente (CAA: 2,3 ± 0,2 e 2,5 ± 0,3, respectivamente). No entanto, os tratamentos F2 e F3 promoveram melhores resultados comparados ao tratamento F1 (ganho em peso: 8,4 ± 1,1 g; TCE = 1,4 ± 0,2%; CAA = 3,2 ± 0,6) (p 0,05). O coeficiente de variação foi inversamente proporcional ao aumento da frequência alimentar. Não houve diferença significativa para taxa de sobrevivência, sendo superior a 90% em todos os tratamentos. Este trabalho sugereque o desempenho do crescimento de juvenis de bijupirá criados em condições do presente estudo pode ser otimizado quando alimentados duas vezes ao dia, facilitando os procedimentos de criaçãoe minimizando os custos relacionados com mão-de-obra e embarcação.

Frequência alimentar e densidade de estocagem para juvenis de robalo-peva em tanques-rede / Feeding frequency and stocking density for fat snook juveniles reared in net cages

In order to evaluate the effect of feeding frequency and stocking density on the zootechnical parameters, juvenile fat snook (3.0 ± 0.96 g and 6.8 ± 0.67 cm) were distributed in 12 groups of fish in four treatments: (T1A) 100 fishes m-³ and 2 meals day-1; (T1B) 100 fish m-³ and 4 meals day-1; (T2A) 200 fish m-³ and 2 meals day-1 and (T2B) 200 fish m-³ and 4 meals day-1. Food was offered to apparent satiation during the experimental period of 90 days. Fish weight and length were determined every 30 days. At the end of the experiment, survival rates ranged from 85 to 89%, with no difference among the treatments (p>0.05). Total length and condition factor values were similar among the treatments (p>0.05), being 12.6 ± 0.27 cm and 0.98 ± 0.05, respectively. Weight gain varied between T2A and T2B treatments (p 0.05). Apparent feed conversion started to differ from 60-days of cultivation between the juveniles stocked at 100 and 200 fish m-³ (p 0.05), being better at the lowest density (2.2). It is recommended to use the feeding frequency of 4 times daily and the stocking density of 200 fish m-3 during the nursery phase, as at this density, although the worst conversion rate was observed (3.1), final biomass value was 2 times higher (3.5 kg) compared to the lower stocking density (1.75 kg).(AU)

Com o objetivo de avaliar o efeito da frequência alimentar e da densidade de estocagem nos parâmetros zootécnicos, juvenis de robalo-peva (3,0 ± 0,96 g e 6,8 ± 0,67 cm) foram distribuيdos em 12 grupos de peixes em quatro tratamentos: (T1A) 100 peixes m-³ e 2 refeiçُes dia-1; (T1B) 100 peixes m-³ e 4 refeiçُes dia-1; (T2A) 200 peixes m-³ e 2 refeiçُes dia-1 e (T2B) 200 peixes m-³ e 4 refeiçُes dia-1. O alimento foi fornecido até a saciedade aparente, durante o perيodo experimental de 90 dias. O peso e comprimento foram avaliados em intervalos de 30 dias. Ao final do experimento, as taxas de sobrevivência variaram de 85 a 89%, sem diferença entre os tratamentos (p>0,05). Os valores de comprimento total e fator de condiçمo foram similares entre os diferentes tratamentos aos 90 dias (p>0,05), sendo 12,6 ± 0,27 cm e 0,98 ± 0,05, respectivamente. O ganho de peso diferiu ao final do experimento entre os tratamentos T2A e T2B . A conversمo alimentar aparente diferiu a partir dos 60 dias entre os juvenis estocados em 100 e 200 peixes m-³ (p 0,05), sendo melhor para a menor densidade (2,2). Recomenda-se a utilizaçمo da frequência alimentar de 4 refeiçُes dia-1 e da densidade de estocagem de 200 peixes m-3 durante a fase de pré-engorda, pois nesta densidade, apesar da pior conversمo alimentar apresentada (3,1), a biomassa final foi 2 vezes maior (3,5 kg) em relação a menor densidade de estocagem (1,75 kg).(AU)

Frequência alimentar e densidade de estocagem para juvenis de robalo-peva em tanques-rede / Feeding frequency and stocking density for fat snook juveniles reared in net cages

In order to evaluate the effect of feeding frequency and stocking density on the zootechnical parameters, juvenile fat snook (3.0 ± 0.96 g and 6.8 ± 0.67 cm) were distributed in 12 groups of fish in four treatments: (T1A) 100 fishes m-³ and 2 meals day-1; (T1B) 100 fish m-³ and 4 meals day-1; (T2A) 200 fish m-³ and 2 meals day-1 and (T2B) 200 fish m-³ and 4 meals day-1. Food was offered to apparent satiation during the experimental period of 90 days. Fish weight and length were determined every 30 days. At the end of the experiment, survival rates ranged from 85 to 89%, with no difference among the treatments (p>0.05). Total length and condition factor values were similar among the treatments (p>0.05), being 12.6 ± 0.27 cm and 0.98 ± 0.05, respectively. Weight gain varied between T2A and T2B treatments (p 0.05). Apparent feed conversion started to differ from 60-days of cultivation between the juveniles stocked at 100 and 200 fish m-³ (p 0.05), being better at the lowest density (2.2). It is recommended to use the feeding frequency of 4 times daily and the stocking density of 200 fish m-3 during the nursery phase, as at this density, although the worst conversion rate was observed (3.1), final biomass value was 2 times higher (3.5 kg) compared to the lower stocking density (1.75 kg).

Com o objetivo de avaliar o efeito da frequência alimentar e da densidade de estocagem nos parâmetros zootécnicos, juvenis de robalo-peva (3,0 ± 0,96 g e 6,8 ± 0,67 cm) foram distribuيdos em 12 grupos de peixes em quatro tratamentos: (T1A) 100 peixes m-³ e 2 refeiçُes dia-1; (T1B) 100 peixes m-³ e 4 refeiçُes dia-1; (T2A) 200 peixes m-³ e 2 refeiçُes dia-1 e (T2B) 200 peixes m-³ e 4 refeiçُes dia-1. O alimento foi fornecido até a saciedade aparente, durante o perيodo experimental de 90 dias. O peso e comprimento foram avaliados em intervalos de 30 dias. Ao final do experimento, as taxas de sobrevivência variaram de 85 a 89%, sem diferença entre os tratamentos (p>0,05). Os valores de comprimento total e fator de condiçمo foram similares entre os diferentes tratamentos aos 90 dias (p>0,05), sendo 12,6 ± 0,27 cm e 0,98 ± 0,05, respectivamente. O ganho de peso diferiu ao final do experimento entre os tratamentos T2A e T2B . A conversمo alimentar aparente diferiu a partir dos 60 dias entre os juvenis estocados em 100 e 200 peixes m-³ (p 0,05), sendo melhor para a menor densidade (2,2). Recomenda-se a utilizaçمo da frequência alimentar de 4 refeiçُes dia-1 e da densidade de estocagem de 200 peixes m-3 durante a fase de pré-engorda, pois nesta densidade, apesar da pior conversمo alimentar apresentada (3,1), a biomassa final foi 2 vezes maior (3,5 kg) em relação a menor densidade de estocagem (1,75 kg).

Outbreak of mortality among cage-reared cobia (Rachycentron canadum) associated with parasitism / Surto de mortalidade em bijupirá (Rachycentron canadum) criado em tanque-rede associado ao parasitismo

This study reports a disease outbreak among juvenile cobia (Rachycentron canadum) farmed in cages in the state of Rio de Janeiro, Brazil, caused by the dinoflagellate Amyloodinium ocellatum and the monogenean Neobenedenia melleni. Two thousand five hundred fish were stocked at 0.4 kg/m3 in a set of 12 m3 tanks, in autumn (mean weight 15.0 ± 7.3 g) and in winter (mean weight 43.0 ± 5.6 g). Freshwater baths were administered as a routine treatment, as the symptoms were detected followed by two collection samples. Firstly in May 2011 (n = 5) and secondly in September 2011 (n = 10). In the first sample, the prevalence of N. melleni on the body surface was 100% and the mean intensity was 42.0 ± 1.7, while in the second sample the prevalence was 60% with a mean intensity 3.0 ± 0.2 and mean abundance 1.8 ± 0.4. Amyloodinium ocellatum was only found in the second sample, at a prevalence 100% and mean intensity 46.8 ± 3.4. The cause of fish mortality was possibly associated with a decrease in fish resistance after the first contact with monogenean parasites, allied with respiratory difficulty caused by the presence of A. ocellatum in the gills.

Este estudo relata a mortalidade em massa de juvenis de bijupirá (Rachycentron canadum) criados em tanques-rede no estado do Rio de Janeiro, Brasil, causada pelo dinoflagelado Amyloodinium ocellatum e o monogenea Neobenedenia melleni. Dois mil e quinhentos peixes estavam estocados à densidade de 0,4 kg/m3 em tanques-rede de 12 m3, no período do outono (15,0 ± 7,3 g; peso médio ± DP) e inverno (peso médio de 43,0 ± 5,6 g). Banhos de água doce foram realizados rotineiramente à medida que os sintomas eram detectados, quando então, foram efetuadas duas colheitas, sendo a primeira em maio de 2011 (n = 5) e a segunda em setembro de 2011 (n = 10). Na primeira colheita, a prevalência de N. melleni foi de 100% e a intensidade média de 42,0 ± 1,7, e na segunda, a prevalência foi de 60% e intensidade média de 3,0 ± 0,2 e abundância média de 1,8 + 0,4. Na segunda colheita, observou-se a presença de A. ocellatum (prevalência de 100%, intensidade média de 46,8 ± 3,4). Possivelmente, a causa da mortalidade estava relacionada à redução na resistência dos peixes após o primeiro contato com o parasito monogenea, juntamente com a dificuldade respiratória causada pelo dinoflagelado nas brânquias.

Monoculture of the ciliate protozoan Euplotes sp. (Ciliophora; Hypotrichia) fed with different diets / Monocultivo do protozoário ciliado Euplotes sp. (Ciliophora; Hypotrichia) com diferentes dietas

Ciliate protozoa of the genus Euplotes commonly appears contaminating mass cultures of rotifers but also with potential to be used as live food in the larviculture of marine fish. To obtain a monoculture of Euplotes sp., three diets were tested: 1) microalgae Nannochloropsis oculata, 2) commercial diet for rotifers Culture Selco 3000, and 3) bakers yeast (Saccharomyces cerevisiae). The ciliates were inoculated at 10 ind. mL-¹. On day 5, protozoa densities in the groups fed the commercial diet (1,911.0 ± 248.7 ind. mL-¹) and the bakers yeast (2,600.0 ± 195.3 ind. mL-1) did not differ, but were higher than the group fed microalgae (2.0 ± 1.4 ind. mL-1) (p 0.05). On day 6, the density in the group fed bakers yeast was higher (15,484.0 ± 1,164.9 ind. mL-¹) than in the groups fed microalgae (3.0 ± 1.4 ind. mL-¹) or commercial diet (11,287.0 ± 1,468.0 ind. mL-¹). An exponential growth curve was observed for the protozoa fed bakers yeast (R² = 0.992; p 0.05) and commercial diet (R² = 0.979; p 0.05). The microalgae diet did not result in satisfactory growth of the protozoan. Feeding bakers yeast or commercial rotifers diet to a monoculture of Euplotes sp. can result in very high densities of this protozoan.(AU)

Protozoários ciliados do gênero Euplotes comumente aparecem como contaminante em culturas massivas de rotíferos, apresentando potencial para ser utilizado na larvicultura de peixes marinhos. Para obter um monocultivo de Euplotes sp., foram testados três tipos de alimento: 1) microalga Nannochloropsis oculata, 2) dieta comercial para rotíferos Culture Selco 3000, e 3) fermento biológico (Saccharomyces cerevisiae). Os ciliados foram inoculados na concentração de 10 indivíduos mL-¹. No quinto dia, a densidade de protozoários nos tratamentos com dieta comercial para rotíferos (1.911,0 ± 248,7 ind. mL-¹; média ± desvio padrão) e fermento biológico (2.600,0 ± 195,3) não diferiram entre si, mas foram superiores ao tratamento com microalga (2,0 ± 1,4) (p 0,05). Ao sexto dia de cultivo, a densidade no tratamento com fermento (15.484,0 ± 1.164,9 ind. mL-¹) foi superior aos tratamentos com microalga (3,0 ± 1,4 ind. mL-¹) e dieta comercial (11.287,0 ± 1.468,0 ind. mL-¹). O cultivo destes ciliados apresentou uma curva de crescimento exponencial para o fermento (R² = 0,992; p 0,05) e a dieta comercial (R² = 0,979; p 0,05). O uso da microalga N. oculata não resultou em crescimento satisfatório destes organismos. O uso de fermento biológico e dieta comercial para rotíferos no monocultivo de Euplotes sp., pode resultar em altas densidades do protozoário.(AU)

Monoculture of the ciliate protozoan Euplotes sp. (Ciliophora; Hypotrichia) fed with different diets / Monocultivo do protozoário ciliado Euplotes sp. (Ciliophora; Hypotrichia) com diferentes dietas

Ciliate protozoa of the genus Euplotes commonly appears contaminating mass cultures of rotifers but also with potential to be used as live food in the larviculture of marine fish. To obtain a monoculture of Euplotes sp., three diets were tested: 1) microalgae Nannochloropsis oculata, 2) commercial diet for rotifers Culture Selco 3000, and 3) baker's yeast (Saccharomyces cerevisiae). The ciliates were inoculated at 10 ind. mL -¹. On day 5, protozoa densities in the groups fed the commercial diet (1,911.0 ± 248.7 ind. mL-¹) and the baker's yeast (2,600.0 ± 195.3 ind. mL-1) did not differ, but were higher than the group fed microalgae (2.0 ± 1.4 ind. mL-1) (p < 0.05). On day 6, the density in the group fed baker's yeast was higher (15,484.0 ± 1,164.9 ind. mL-¹) than in the groups fed microalgae (3.0 ± 1.4 ind. mL-¹) or commercial diet (11,287.0 ± 1,468.0 ind. mL-¹). An exponential growth curve was observed for the protozoa fed baker's yeast (R² = 0.992; p < 0.05) and commercial diet (R² = 0.979; p < 0.05). The microalgae diet did not result in satisfactory growth of the protozoan. Feeding baker's yeast or commercial rotifer's diet to a monoculture of Euplotes sp. can result in very high densities of this protozoan.

Protozoários ciliados do gênero Euplotes comumente aparecem como contaminante em culturas massivas de rotíferos, apresentando potencial para ser utilizado na larvicultura de peixes marinhos. Para obter um monocultivo de Euplotes sp., foram testados três tipos de alimento: 1) microalga Nannochloropsis oculata, 2) dieta comercial para rotíferos Culture Selco 3000, e 3) fermento biológico (Saccharomyces cerevisiae). Os ciliados foram inoculados na concentração de 10 indivíduos mL-¹. No quinto dia, a densidade de protozoários nos tratamentos com dieta comercial para rotíferos (1.911,0 ± 248,7 ind. mL-¹; média ± desvio padrão) e fermento biológico (2. 600,0 ± 195,3) não diferiram entre si, mas foram superiores ao tratamento com microalga (2,0 ± 1,4) (p < 0,05). Ao sexto dia de cultivo, a densidade no tratamento com fermento (15.484,0 ± 1.164,9 ind. mL-¹) foi superior aos tratamentos com microalga (3,0 ± 1,4 ind. mL-¹) e dieta comercial (11.287,0 ± 1.468,0 ind. mL-¹). O cultivo destes ciliados apresentou uma curva de crescimento exponencial para o fermento (R² = 0,992; p < 0,05) e a dieta comercial (R² = 0,979; p < 0,05). O uso da microalga N. oculata não resultou em crescimento satisfatório destes organismos. O uso de fermento biológico e dieta comercial para rotíferos no monocultivo de Euplotes sp., pode resultar em altas densidades do protozoário.

Outbreak of mortality among cage-reared cobia (Rachycentron canadum) associated with parasitism.

This study reports a disease outbreak among juvenile cobia (Rachycentron canadum) farmed in cages in the state of Rio de Janeiro, Brazil, caused by the dinoflagellate Amyloodinium ocellatum and the monogenean Neobenedenia melleni. Two thousand five hundred fish were stocked at 0.4 kg/m3 in a set of 12 m3 tanks, in autumn (mean weight 15.0 ± 7.3 g) and in winter (mean weight 43.0 ± 5.6 g). Freshwater baths were administered as a routine treatment, as the symptoms were detected followed by two collection samples. Firstly in May 2011 (n = 5) and secondly in September 2011 (n = 10). In the first sample, the prevalence of N. melleni on the body surface was 100% and the mean intensity was 42.0 ± 1.7, while in the second sample the prevalence was 60% with a mean intensity 3.0 ± 0.2 and mean abundance 1.8 ± 0.4. Amyloodinium ocellatum was only found in the second sample, at a prevalence 100% and mean intensity 46.8 ± 3.4. The cause of fish mortality was possibly associated with a decrease in fish resistance after the first contact with monogenean parasites, allied with respiratory difficulty caused by the presence of A. ocellatum in the gills.

Comparative effect of benzocaine, menthol and eugenol as anesthetics for juvenile fat snook / Efeito comparativo da benzocaína, mentol e eugenol como anestésicos para juvenis de robalo peva

The present study evaluated different concentrations of benzocaine, eugenol and menthol for induction of anesthesia in juveniles fat snook (Centropomus parallelus), aiming to determine the most suitable product in terms of induction and recovery time, and the minimum optimal dose for each anesthetic. Concentrations of 50, 75, 100 and 150 mg L-1 of benzocaine; 25, 37.5, 62.5 and 50 mg L-1 of eugenol and 50, 100, 150 and 200 mg L-1 of menthol were tested at 21°C. During the procedure of anesthesia, four stages, from reduction of opercular movements to total loss of reaction to stimulus were monitored. While anesthetized, fish were subjected to biometric procedure and then were placed in an aquarium anesthetic free, to observe the recovery time.  Concentrations of 75, 37.5 and 150 mg L-1 of benzocaine, eugenol and menthol, respectively, were considered optimal. By presenting several qualities as an anesthetic and also because it can be used efficiently (time to anesthesia in approximately three minutes and recovery in less than five minutes) at low concentrations, eugenol is the most recommended for anesthesia of juvenile fat snook.

Foram avaliadas diferentes concentrações de benzocaína, eugenol e mentol na indução anestésica em juvenis do robalo-peva (Centropomus parallelus), a fim de determinar o produto mais adequado em termos de tempo de indução e recuperação e o mínimo ótimo de cada anestésico. Foram testadas as concentrações de 50, 75, 100 e 150 mg L-1 de benzocaína, 25; 37,5; 50 e 62,5 mg L-1 de eugenol e 50, 100, 150 e 200 mg L-1 de mentol a 21°C. Durante o procedimento de anestesia, quatro estágios, da redução dos movimentos operculares até a perda total de reação ao estímulo, foram monitorados. Enquanto anestesiados, os peixes foram submetidos ao processo de biometria e, em seguida, colocados em um aquário com água limpa, sem anestésico, para observação do tempo de recuperação. As concentrações de 75; 37,5 e 150 mg L-1 de benzocaína, eugenol e mentol, respectivamente, foram consideradas ótimas. Por apresentar diversas qualidades como anestésico e poder ser utilizado com eficiência (tempo de anestesia em aproximadamente três minutos e recuperação em menos de cinco minutos) em baixas concentrações, o eugenol apresentou a melhor relação custo benefício para a anestesia de juvenis de robalo-peva.

Comparative effect of benzocaine, menthol and eugenol as anesthetics for juvenile fat snook / Efeito comparativo da benzocaína, mentol e eugenol como anestésicos para juvenis de robalo peva

The present study evaluated different concentrations of benzocaine, eugenol and menthol for induction of anesthesia in juveniles fat snook (Centropomus parallelus), aiming to determine the most suitable product in terms of induction and recovery time, and the minimum optimal dose for each anesthetic. Concentrations of 50, 75, 100 and 150 mg L-1 of benzocaine; 25, 37.5, 62.5 and 50 mg L-1 of eugenol and 50, 100, 150 and 200 mg L-1 of menthol were tested at 21°C. During the procedure of anesthesia, four stages, from reduction of opercular movements to total loss of reaction to stimulus were monitored. While anesthetized, fish were subjected to biometric procedure and then were placed in an aquarium anesthetic free, to observe the recovery time.  Concentrations of 75, 37.5 and 150 mg L-1 of benzocaine, eugenol and menthol, respectively, were considered optimal. By presenting several qualities as an anesthetic and also because it can be used efficiently (time to anesthesia in approximately three minutes and recovery in less than five minutes) at low concentrations, eugenol is the most recommended for anesthesia of juvenile fat snook.

Foram avaliadas diferentes concentrações de benzocaína, eugenol e mentol na indução anestésica em juvenis do robalo-peva (Centropomus parallelus), a fim de determinar o produto mais adequado em termos de tempo de indução e recuperação e o mínimo ótimo de cada anestésico. Foram testadas as concentrações de 50, 75, 100 e 150 mg L-1 de benzocaína, 25; 37,5; 50 e 62,5 mg L-1 de eugenol e 50, 100, 150 e 200 mg L-1 de mentol a 21°C. Durante o procedimento de anestesia, quatro estágios, da redução dos movimentos operculares até a perda total de reação ao estímulo, foram monitorados. Enquanto anestesiados, os peixes foram submetidos ao processo de biometria e, em seguida, colocados em um aquário com água limpa, sem anestésico, para observação do tempo de recuperação. As concentrações de 75; 37,5 e 150 mg L-1 de benzocaína, eugenol e mentol, respectivamente, foram consideradas ótimas. Por apresentar diversas qualidades como anestésico e poder ser utilizado com eficiência (tempo de anestesia em aproximadamente três minutos e recuperação em menos de cinco minutos) em baixas concentrações, o eugenol apresentou a melhor relação custo benefício para a anestesia de juvenis de robalo-peva.

Economic feasibility of clown fish, Amphiprion ocellaris, in recirculation system / Viabilidade econômica do cultivo do peixe palhaço, Amphiprion ocellaris, em sistema de recirculação

Little known in Brazil, the marine ornamental fish production has characteristics for generating employment and income for small entrepreneurs. This study analyzes the economic viability of the clown fish, Amphiprion ocellaris, in a recirculating water system at Florianópolis, Brazil. For evaluate the cost of production, the effective operational cost (EOC), total operational cost (TOC) and the total cost of production (TCP) were considered. The indexes for the evaluation of the profitability were the internal return rate (IRR) and the pay-back. The labor represents the major operational cost, about 40%. The internal return rate (IRR) was 37.15 and 58.23% and pay-back 25 and 33 months, respectively for the two market prices of R$ 25.00 and R$ 30.00. The small-scale production in recirculation system is economically viable, with attractive profitability indicators when compared to other aquaculture ventures.

Pouco difundida no Brasil, a criação de peixes ornamentais marinhos apresenta características que favorecem a geração de trabalho e renda para pequenos empreendedores. Este estudo analisou a viabilidade econômica do cultivo do peixe palhaço, Amphiprion ocellaris, em sistema de recirculação de água, em Florianópolis, Brasil. Para dimensionar os custos de produção foram considerados o custo operacional efetivo (COE), custo operacional total (COT) e custo total de produção (CTP). Os índices para a avaliação da rentabilidade foram a taxa interna de retorno e o pay-back. A mão-de-obra representou o principal custo operacional, cerca de 40%. A taxa interna de retorno (TIR) foi de 37,15 e 58,23% e o pay-back de 25 e 33 meses, respectivamente para os dois preços de venda praticados: R$ 25,00 e R$ 30,00. O cultivo em pequena escala em sistema de recirculação de água mostrou-se economicamente viável, apresentando indicadores de rentabilidade atraentes quando comparado a outros empreendimentos aquícolas.

Economic feasibility of clown fish, Amphiprion ocellaris, in recirculation system / Viabilidade econômica do cultivo do peixe palhaço, Amphiprion ocellaris, em sistema de recirculação

Little known in Brazil, the marine ornamental fish production has characteristics for generating employment and income for small entrepreneurs. This study analyzes the economic viability of the clown fish, Amphiprion ocellaris, in a recirculating water system at Florianópolis, Brazil. For evaluate the cost of production, the effective operational cost (EOC), total operational cost (TOC) and the total cost of production (TCP) were considered. The indexes for the evaluation of the profitability were the internal return rate (IRR) and the pay-back. The labor represents the major operational cost, about 40%. The internal return rate (IRR) was 37.15 and 58.23% and pay-back 25 and 33 months, respectively for the two market prices of R$ 25.00 and R$ 30.00. The small-scale production in recirculation system is economically viable, with attractive profitability indicators when compared to other aquaculture ventures.

Pouco difundida no Brasil, a criação de peixes ornamentais marinhos apresenta características que favorecem a geração de trabalho e renda para pequenos empreendedores. Este estudo analisou a viabilidade econômica do cultivo do peixe palhaço, Amphiprion ocellaris, em sistema de recirculação de água, em Florianópolis, Brasil. Para dimensionar os custos de produção foram considerados o custo operacional efetivo (COE), custo operacional total (COT) e custo total de produção (CTP). Os índices para a avaliação da rentabilidade foram a taxa interna de retorno e o pay-back. A mão-de-obra representou o principal custo operacional, cerca de 40%. A taxa interna de retorno (TIR) foi de 37,15 e 58,23% e o pay-back de 25 e 33 meses, respectivamente para os dois preços de venda praticados: R$ 25,00 e R$ 30,00. O cultivo em pequena escala em sistema de recirculação de água mostrou-se economicamente viável, apresentando indicadores de rentabilidade atraentes quando comparado a outros empreendimentos aquícolas.