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ABSTRACT: The environmental regulation of continental fish farming in Brazil is closely linked to land occupation and use. Areas used for this activity are mostly located in permanent preservation areas (PPA), close to rivers and springs, demonstrating the necessity of regulating this activity for its compliance with public policy. Santa Catarina is a leading state in fish farming and one of the first to regulate the use of PPAs. The feasibility of a proposal for environmental compensation to regularize the use of PPAs in Santa Catarina for fish farming; was therefore, assessed. The results showed that 74% of the fish farms analyzed need to regularize the occupation of production structures in PPAs. Regarding the proposed index of compensation for use in PPAs, the environmental compensation factor (ECF), through evaluation of the individual maps and subsequent integrated evaluation, all the fish farms identified with environmental liabilities in occupation had ratios of 1:2 and 1:3, and this index is a viable alternative for environmental regularization of the activity. It was further proposed that ECF be applied to small fish farms of up to four fiscal modules and that they have a standard minimum occupancy profile in relation to the total area of the property, as assessed in the present study.

This study explored ultrasonography, exfoliative cytology, and celiotomy as methods for sex determination in Pimelodus maculatus, a species included in fish-stocking programs aimed at conserving and recovering populations affected by hydroelectric power plant activity. Three-year-old fish (n=40), with an average weight of 81.3 ± 16.6 g and average length of 18.9 ± 1.2 cm, were examined in series, according to the degree of invasiveness of these techniques. Ultrasonography showed the ovaries as structures with smooth and defined margins and hypoechoic and homogeneous parenchyma, while the testes were isoechoic to the adjacent structures. Cytology of the urogenital region revealed cellular elements with an accuracy rate of 80 % for females and zero for males. In celiotomy, 100 % accuracy in sex determination was achieved, with 100 % survival after 30 days, indicating rapid recovery. This study provides new insights into the applicability of methodologies for determining the sex of P. maculatus, thereby contributing to the management and conservation of this species.

We aimed to identify the digestive microbiota of the golden mussel Limnoperna fortunei, and characterize its structure in different seasons. Limnoperna fortunei specimens were sampled in winter (September 2019) and summer (March 2020) in five reservoirs of hydroelectric power plants in southern Brazil. In each reservoir, we sampled 15 individuals at three different points. We collected the digestive diverticulum and portions of the intestine for bacterial DNA extraction, and subsequently conducted metagenomic analysis. The intestinal microbial communities of L. fortunei occurring in the upper Uruguay River region showed significant differences during winter and summer. Although the phyla Proteobacteria, Bacteroidetes, and Cyanobacteria were dominant regardless of the season, the microbial communities showed greater richness and bacterial diversity in the summer. Additionally, we found 143 species of bacteria in the digestive samples collected during both winter and summer, which may indicate a central microbial community for the species. The microbial communities in the digestive tract of L. fortunei showed greater bacterial richness and diversity in summer samples, which existed at a significantly higher temperature than those in winter samples. We observed seasonal variations in the microbiota of L. fortunei in the upper Uruguay River region, with increased bacterial richness and diversity in the digestive tract during summer, attributed to higher temperatures. However, Proteobacteria, Bacteroidetes, and Cyanobacteria consistently dominated the digestive tract of the golden mussel, regardless of seasonal fluctuations.

Abstract Aim This study aimed to evaluate the spatial and temporal distribution of ichthyoplankton in the Peri Lagoon, a coastal freshwater lagoon in Brazil. Methods Ichthyoplankton samples were collected every two months from June 2008 to April 2010 with 500 µm conical-cylindrical planktonic nets at five sampling stations. Results In total, 181 fish eggs and 1,315 larvae, representing estuarine and freshwater species, were captured. The most representative species were Awaous tajasica, Ctenogobius sp1, and Platanichthys platana. Significant differences were found in temporal egg distribution and larval spatiotemporal distribution (Kruskal-Wallis test, p < 0.05). Eggs were predominantly captured during the autumn, winter, and spring Neotropical seasons. Geospatial analysis demonstrated spatial segregation in the distribution of larval assemblages, with higher abundances in areas adjacent to riparian forests, following stream mouths, and deeper areas with rocky substrates. Conclusions Proximity to streams and areas surrounded by dense forests is crucial for the spawning and development of fish species in the Peri Lagoon. The findings of this study provide valuable insights into the conservation of the ichthyofauna in this unique environment.

Abstract This study investigated injuries sustained by Pimelodus maculatus caused by transient operating conditions in a Brazilian hydroelectric power plant. Fish (n = 43) that inhabited the tailrace and appeared on the water surface after changes in the operating conditions were evaluated (IF). Additionally, fish (n = 10) captured using longline in the vicinity of the tailrace were used for comparisons (NF). Blood samples were evaluated for cortisol, glucose, and lactate concentrations. Tissue samples (gill, liver, brain, and muscle) were analyzed for oxidative stress biomarkers (TBARS, protein carbonyl content, and catalase activity) and histology (gill, liver, and spleen). The most prominent findings in IF were barotraumas with intra-abdominal hemorrhage and swim bladder rupture. Cortisol and glucose concentrations were lower for IF when compared to NF. IF also suffered from oxidative stress, as indicated by increased TBARS in the liver and brain, as well as increased protein carbonyl content in the gills and liver. The main histological alterations induced by the adverse conditions were circulatory disorders, such as telangiectasia and gill aneurysm, hepatic congested veins, and hemorrhage in the liver and spleen. The abrupt drop of pressure resulting from changes in the operating conditions of the turbines caused barotraumas and oxidative stress, which were the leading causes of fish mortality

ABSTRACT Pirarucu, Arapaima gigas is a fish species of great social and economic importance in the Amazon region, where they are often farmed in earthen ponds. Intensive cage aquaculture has been growing in Brazil, which could be an alternative means to farm pirarucu, reducing costs and increasing productivity. We evaluated the contribution of natural food organisms in semi-intensive (ponds) and intensive (cages) production systems, and their effect on pirarucu growth and economic performance during the first phase of grow-out. Four ponds (300 m2) and four cages (4.0 m³) were stocked, respectively, with 120 (0.4 fish m-²) and 160 (40 fish m-³) juvenile pirarucu (28.03 ± 6.34 g, 11.75 ± 0.80 cm). The study was conducted for 105 days and fish were fed with commercial feed. Fish growth and plankton intake were evaluated every two weeks. Survival rate, standard length, weight gain and final weight were higher in fish reared in earthen ponds than in cages. Feed conversion of fish kept in ponds was lower (0.96 ± 0.06) than in cages (1.20 ± 0.11). The consumption of natural food organisms was observed, despite artificial feed being fed in both systems. The relative abundance of zooplankton and insects in stomachs was directly proportional to fish weight gain in ponds, and inversely proportional in cages. Higher economic efficiency rate and lower average production cost were calculated for earthen ponds. Our results indicate that the cost-benefit of the first phase grow-out of A. gigas is better in earthen ponds.

Com o objetivo de estudar a taxa de sobrevivência e o desenvolvimento de larvas de piracanjuba, Brycon orbignyanus (Characiformes, characidae), foram realizados três experimentos com três repetições por tratamento. Os experimentos consistiram em testar três diferentes estoques iniciais de densidade (5, 15 e 25 larvas de piracanjuba/L), três dietas (Artemia sp, ração comercial e larva de curimbatá, Prochilodus lineatus) e dois formatos de tanque de larvicultura (quadrado e retangular). Os parâmetros de qualidade de água foram medidos duas vezes ao dia. A alimentação foi oferecida em um intervalo de 4 horas, iniciando após a abertura da boca das larvas. Sob as condições de realização deste experimento, conclui-se que as diferentes densidades de estocagem utilizadas, assim como as três diferentes dietas, não influenciaram a sobrevivência, média de peso, comprimento e altura dorso-ventral das larvas de piracanjuba. Entretanto, o comprimento e o peso das larvas, diferentemente dos outros fatores, foi significativamente melhor no tanque de formato quadrado

Abstract: We optimized a methodology for plankton environmental DNA detection of the invasive golden mussel and validated it in samples from a Southern Brazil reservoir. Limnoperna fortunei is a successful invasive alien species that causes significant impacts on freshwater ecosystems. We adjusted and validated the methodology to detect L. fortunei in plankton samples, with a SYBR Green assay. Based on the standard curve analysis, the observed theoretical minimal qPCR detection level was 0.0005625 ng.µL-1 (R2 = 0.99) at a PCR quantification cycle of 14.09–29.56. We also presented a practical guide to be used in monitoring and detection of L. fortunei. The optimized protocol was efficient in detecting L. fortunei and can be used to monitor already infested environments or invasions in new environments.

The transportation of live fish is a routine procedure in aquaculture, and includes a series of stressful stimuli such as an increase in the stocking density of specimens per volume of water, and abrupt changes in water quality. This study evaluated the water quality and the stress levels on Pimelodus maculatus (Lacépède, 1803) fingerlings transported in plastic bags by a mechanical transportation simulator. Fish were stocked at densities 4 (22.88 g/L), 8 fish/L (45.76 g/L) and 12 fish/L (68.64 g/L) and the transportation simulation was performed for 4, 8 or 12 hours. A completely randomized experimental design applied to a 3 x 3 factorial model with three replicates was used. Water quality was evaluated by the analysis of the temperature, pH, conductivity, dissolved oxygen, total ammonia, unionized ammonia and nitrite at the beginning and at the end of the experiment. Stress was assessed by determining tissue cortisol levels by radioimmunoassay, in the beginning and at the end of the study. The densities and the transportation times did not cause mortality, but higher density and times of transport influenced water quality indicators. The simulated transportation of P. maculatus showed that all P. maculatus fingerlings survived at the maximum density tested, 12 fish/L for 12 hours.

This study aimed to evaluate the temporal distribution of fish eggs and larvae in the Forquilha river (upper Uruguay river/Brazil) and its relationship with environmental variables. Ichthyoplankton and abiotic factors were sampled from September 2006 to August 2007. At the laboratory, samples were sorted and larvae were identified to the lowest possible taxonomic level. For data analysis we applied One-way Anova, Tukey’s test, Pearson correlation and PCA. In this study 200 eggs and 308 larvae were collected, showing differences in the temporal distribution and influence of abiotic factors. Larvae were identified in all stages of development, being distributed in three order and eight families. These results point that the lower portion of the Forquilha river is an important drift and nursery area for fish larvae of the upper Uruguay river. The breeding season for most species was greatly marked, between October and January, coinciding with the increase in temperature and decrease of the water flow. The response of reproductive intensity varies according to the environmental variables.

The objective of this work was to evaluate the growth and the stress levels of juvenile dourado (Salminus brasiliensis) cultivated in cages. Fish stocked at densities of 15 (D15) and 30 (D30) fish per square meter were evaluated in a completely randomized design with three replicates. Fish were fed twice a day with extruded ration (42% crude protein). Density influenced only biomass and daily food intake, and glucose and lactate concentrations increased over time. D15 and D30 did not influence the growth of dourado. However, the increase of glucose and lactate levels over time indicates that cultivation in cages is a stressful condition for this species.

This study aimed to evaluate the effects of water temperature duringfertilization and egg incubation in the determination of the sex ratio of fingerlings of silver catfish Rhamdia quelen. Water temperatures of 19, 25 and 30°C were used during the egg fertilizations, and the eggs were then incubated at temperatures of 19, 25 or 30°C for each fertilization temperature condition. An increase in temperature reduced the fertilization rate of R. quelen, while the final number of fish was reduced when a lower temperature was used during egg incubation. The temperatures of fertilization and incubation that were tested did not alter the sex ratio.O presente estudo teve como objetivo avaliar o efeito da temperatura da água de fertilização e de incubação na determinação da proporção sexual do jundiá, Rhamdia quelen. Para tanto, foram utilizadas três temperaturas de água de fertilização de ovos (19, 25 e 30°C), e para cada uma delas os ovos foram incubados nas temperaturas de 19, 25 e 30°C. O aumento da temperatura reduziu a taxa de fertilização de Rhamdia quelen, enquanto o número final de indivíduos foi reduzido quando a menor temperatura de incubação foi utilizada. As temperaturas de fertilização ou incubação testadas não alteram a proporção entre os sexos.

This study aimed to evaluate the influence of densities 8, 32, 56 and 80 fish/m3 on the productive performance of Pimelodus maculatus in 1m3 cages installed in 0.19ha earthen ponds without water renewal, located on private property in Santo Amaro da Imperatriz, Santa Catarina. Fish were fed daily with extruded commercial ration containing 32% of crude protein, in a proportion of 5.0% of the stocked biomass. Fish were sampled monthly (30% of the stocked fish) in each cage to evaluate length, weight, specific growth rate, survival, condition factor and biomass. Final length and weight were the same at densities 8, 32 and 56 fish/m3, with values higher than those registered with 80 fish/m3. The survival was the same at the different densities, with a mean of 91.4 ± 5.4%, whereas a higher biomass was registered with 56 and 80 fish/m3. The results showed that density influences fish growth and indicated 56 fish/m3 as the ideal for the performance of P. maculatus juveniles. However, additional information must be produced to optimize the species biomass production.

O estudo teve por objetivo avaliar a influência das densidades 8, 32, 56 e 80 peixes/m3 sobre o crescimento de Pimelodus maculatus (mandi-amarelo) em tanques-rede de 1m3 instalados em viveiro de terra de 0,19ha, sem renovação de água, localizado em uma propriedade particular em Santo Amaro da Imperatriz, Santa Catarina. Os peixes foram alimentados diariamente com ração comercial extrusada contendo 32% de proteína bruta, na proporção de 5% da biomassa estocada. Foram realizadas biometrias mensais de 30% do número de peixes estocados em cada tanque-rede para avaliação do comprimento total, peso total, crescimento específico, fator de condição, sobrevivência e biomassa. Ao final do experimento o comprimento e o peso foram iguais nas densidades 8, 32 e 56 peixes/m3, e superiores aos registrados com 80 peixes/m3. A sobrevivência foi igual nas diferentes densidades, apresentando média de 91,4 ± 5,4%, sendo que as maiores biomassas foram registradas nas densidades 56 e 80 peixes/m3. Os resultados demonstraram a influência das densidades testadas sobre o crescimento dos peixes e indicaram a densidade de 56 peixes/m3 como a ideal para o crescimento de juvenis de P. maculatus. No entanto muitas informações ainda deverão ser produzidas para otimizar a produção de biomassa desta espécie.

This study aimed to evaluate the influence of photoperiod on juvenile suruvi (Steindachneridion scriptum) in six photoperiods: 24L-0D (L= Light; D= Dark), 18L-6D, 14L-10D, 10L-14D, 6L-18D and 0L-24D. Juveniles measuring 176.8 ± 13.2mm and weighing 60.2 ± 16.0g were distributed in eighteen 150-L aquariums, stocked with 8 juveniles per aquarium. At the end of the study, treatments 24L-0D (105.7 ± 5.8g and 845.9 ±46g) and 0L-24D (93.3 ± 4.9g and 746.4 ± 39.5g) were different (P0.05) in all the treatments. The results showed that suruvi (Steindachneridion scriptum) reached better weight and biomass in extended light periods.O objetivo do presente estudo foi avaliar a influência do fotoperíodo no cultivo de juvenis de suruvi Steindachneridion scriptum, nos seguintes fotoperíodos: 24L-0E (L=Luz; E= Escuro), 18L-6E, 14L-10E, 10L-14E, 6L-18E e 0L-24E. Juvenis com comprimento e peso médio de 176,8± 13,2mm e 60,2± 16,0g, respectivamente, foram distribuídos em 18 tanques de 150L, estocados na densidade de oito juvenis por tanques. Decorridos 90 dias de cultivo foram encontradas diferenças (P0,05) na sobrevivência (100,0 ± 0,0%) e no comprimento total (212,5 ± 2,5mm). Nas condições apresentadas os resultados nos permitem concluir que o suruvi, Steindachneridion scriptum, atingiu melhor peso e biomassa em cultivos que apresentam períodos com iluminação.

The effect of food and photoperiod on dorado (Salminus brasiliensis) post-larvae growth and survival was investigated using the following treatments: LD (Light: Dark) 24:0 + Artemia nauplii (A), LD 24:0 + fish prey (F), LD 14:10 + A, LD 14:10 + F, LD 0:24 +A and LD 0:24 + F. Prochilodus lineatus larvae were used as fish prey. Higher survival rates were registered in fish prey treatments (PO efeito da alimentação e do fotoperíodo sobre o crescimento e a sobrevivência de pós-larvas de dourado (Salminus brasiliensis) foi investigado utilizando-se os seguintes tratamentos: LE (Luz: Escuro) 24:0 + náuplios de Artemia (A), LE 24:0 + larva forrageira (L), LE 14:10 + A, LE 14:10 + L, LE 0:24 +A e LE 0:24 + L. Larvas de Prochilodus lineatus foram utilizadas como larva forrageira. Taxas de sobrevivência mais elevadas foram registradas nos tratamentos que utilizaram larvas forrageiras (P

The genetic variability of four fish species (Pimelodus maculatus, Prochilodus lineatus, Salminus brasiliensis and Steindachneridion scripta) collected in the upper Uruguay River basin was analyzed using the RAPD technique. A total of 118 amplified fragments was obtained, 11 for P. maculatus, 29 for P. lineatus, 45 for S. brasiliensis and 33 for S. scripta. Amplified fragments with monomorphic profile were not found in the studied species, except for S. brasiliensis, which presented seven monomorphic bands for Saltinho population. All species showed high levels of genetic variability among individuals.A diversidade da vida se expressa de modo extraordinário nos ecossistemas aquáticos. A bacia do alto rio Uruguai é um exemplo desta condição, onde há registro de mais de 100 espécies de peixes. A compreensão das diferenças genéticas entre as diversas populações nativas é fundamental para a manutenção de seus estoques. A variabilidade genética de quatro espécies de peixes (Pimelodus maculatus, Prochilodus lineatus, Salminus brasiliensis e Steindachneridion scripta) coletadas na bacia do alto rio Uruguai foi analisada utilizando-se a técnica de RAPD. Obteve-se um total de 118 fragmentos amplificados, sendo 11 para P. maculatus, 29 para P. lineatus, 45 para S. brasiliensis e 33 para S. scripta. Fragmentos de caráter monomórfico não foram encontrados para as espécies estudadas, com exceção de S. brasiliensis de Saltinho que apresentou sete bandas monomórficas para estes indivíduos. As análises estatísticas mostraram altos níveis de variabilidade genética entre os indivíduos das espécies estudadas.

O objetivo deste estudo foi avaliar a sobrevivência e o crescimento de larvas de surubim, Pseudoplatystoma corruscans, em cinco densidades de cultivo: 15, 35, 55, 75 e 95 larvas/L, distribuídas em um delineamento inteiramente ao acaso com três repetições. Utilizou-se água salinizada (5%) para o cultivo. As larvas foram mantidas em ambiente sem luz e alimentadas com náuplios de Artemia sp. na proporção de 500 náuplios/larva/dia. Ao final do experimento (10o dia), a sobrevivência apresentou tendência de redução com oaumento da densidade de estocagem, mas não se verificou relação entre o crescimento e a densidade. As concentrações de amônia não ionizada e de nitrito apresentaram variação diretamente proporcional ao aumento da densidade e podem ter influenciado a sobrevivênciafinal. A maior sobrevivência (52,0 ± 9,3%) foi registrada em cultivo com 15 larvas/L, sendo que essa densidade não produziu efeito negativo sobre a qualidade da água.The aim of this study was to evaluate the survival and the growth of surubim Pseudoplatystoma corruscans larvae in five stocking densities: 15, 35, 55, 75 and 95 larvae/L, distributed in a completely randomized design with three repetitions. Brackish water (5%) was used in the cultivation. The larvae were cultivated without light and fed with 500 Artemia sp. nauplii/larvae/day. At the end of the experiment (10th day), the survival showed tendency to reduction with the increase of the stocking density, but a relationship between growth and density was not registered. The concentrations of non-ionized ammonia and nitrite varied proportionally to density increase and those concentrations probably influenced the final survival. The highest survival (52.0 ± 9.3%) was registered at 15 larvae/L, a density that did not produce negative effect on the quality of water.

O objetivo deste estudo foi avaliar o crescimento de alevinos de jundiá, Rhamdia quelen, em 5 concentrações de oxigênio dissolvido: 1,3 (T1), 2,4 (T2), 3,7 (T3), 5,4 (T4) e 7,5 mg O2/L (T5). O estudo utilizou o modelo experimental inteiramente ao acaso com 3 repetições e foi conduzido por 25 dias. Os alevinos foram distribuídos em tanques circulares de fibra de vidro de 150 L mantidos na escuridão e dotados de aeração mecânica, filtro biológico e renovação de água, nadensidade de 34 indivíduos/tanque. A sobrevivência foi menor nos extremos testados (T1 e T5). Maior crescimento em peso e em comprimento e melhor conversão alimentar foram obtidos com o aumento da concentração de oxigênio dissolvido. Os alevinos de jundiá apresentaram incremento em peso, mesmo na menor concentração de oxigênio dissolvido (T1), e T4 produziu os melhores efeitos sobre o desenvolvimento.This study's aim was evaluate the growth of silver catfish (Rhamdia quelen) fingerlings on five dissolved oxygen concentrations: 1,3 (T1), 2,4 (T2), 3,7 (T3), 5,4 (T4) and 7,5 mg O2/L (T5). A completely random design experiment with three repetitions was used and the experiment was carried out during 25 days. Fingerlings were distributed in circular, 150-L fiberglass tanks kept in darkness, endowed with mechanic and biological filters and water renewal, at a stocking density of 34 individuals/tank. Survival was lower at the extreme tested levels (T1 and T5). Better growth in weight, length and food conversion were found at increasing oxygen concentrations. Even at the lowest oxygen concentration (T1) fingerlings showed growth increase. The best effects on silver catfish fingerlings development was observed at T4.

This study evaluated the biochemical changes associated to successive captures of Salminus brasiliensis reared at different stocking densities. The experiment was conducted in tanks with a capacity of 1,000 L, connected to a recirculating system with temperature control and continuous aeration. Fish were stocked at densities of 30, 150 and 300 fish m-3 and the successive catches were applied at the end of the experimental period of 80 days. The biochemical changes were evaluated at the end of the trial through the parameters: hematocrit, hemoglobin, glucose and lactate in plasma and Na+, K+ and Cl- and Ca2+ in the gills. The concentration of glucose increased with the increase of stocking density as also registered for lactate concentration, except for fish captured twice. Hemoglobin concentration increased with the increase of stocking density only in fish captured three times. The hematocrit and the ions in the gills had no variation under any condition and therefore, the ionic alterations characteristic of a stress response, were not found in this species. The successive captures associated to stocking density were related to biochemical changes in S. brasiliensis, but ion concentrations in gills were not indicators of this condition.

This study aimed to evaluate the effects of water temperature during fertilization and egg incubation in the determination of the sex ratio of fingerlings of silver catfish Rhamdia quelen. Water temperatures of 19, 25 and 30°C were used during the egg fertilizations, and the eggs were then incubated at temperatures of 19, 25 or 30°C for each fertilization temperature condition. An increase in temperature reduced the fertilization rate of R. quelen, while the final number of fish was reduced when a lower temperature was used during egg incubation. The temperatures of fertilization and incubation that were tested did not alter the sex ratio.

O objetivo deste estudo foi verificar a influência do fotoperíodo no cultivo de pós-larvas de piracanjuba Brycon orbignyanus (Valenciennes, 1849) (Osteichthyes, Characidae), submetidas a quatro tratamentos: 0L-24E (L=Luz; E= Escuro), 10L-14E, 14L-10E e 24L-0E, com três 3 repetições. Pós-larvas com comprimento de 7,8±0,7mm e com peso de 3,5±0,8mg foram distribuídas em 12 aquários de 10L, estocados com 12 pós-larvas por aquário. Os indivíduos foram diariamente alimentados com naúplios de Artemia, ao longo dos 10 dias de experimento. Ao final, observou-se relação positiva entre a sobrevivência e o aumento do período com luz, sendo o maior valor de sobrevivência 88,9±9,7%, obtido no tratamento com 24 horas de luminosidade, e o menor valor 58,3±8,3%, no tratamento com 24 horas em escuridão. O comprimento e peso das pós-larvas de piracanjuba não apresentaram diferenças significativas (P>0,05) entre os diferentes tratamentos, porém foi observada uma maior heterogeneidade entre as pós-larvas cultivadas com maior período de escuridão.

A influência do pH sobre o desenvolvimento de ovos e larvas de jundiá (Rhamdia quelen, Quoy e Gaimard, 1824) foi avaliada utilizando-se experimentos inteiramente casualizados com 6 tratamentos (pH 4, 5, 6, 7, 8 e 9), em três desovas. Todos os ovos incubados em pH 4 morreram, o mesmo acontecendo quando a temperatura atingiu 17ºC. Nas desovas com temperatura semelhante os diferentes tratamentos não apresentaram diferença com relação à taxa de fertilização, enquanto na desova que apresentou maior temperatura, os pH 6 e 7 apresentaram a menor taxa. O tempo de eclosão das larvas foi diretamente proporcional à temperatura, e, após a eclosão, todas as larvas submetidas ao pH 5 morreram. O tempo para abertura da boca foi influenciado pela temperatura, e não pelos tratamentos. A taxa de sobrevivência sofreu influência do pH nas diferentes condições de temperatura da água

O objetivo deste estudo foi avaliar o crescimento de alevinos de jundiá, Rhamdia quelen, em 5 concentrações de oxigênio dissolvido: 1,3 (T1), 2,4 (T2), 3,7 (T3), 5,4 (T4) e 7,5 mg O2/L (T5). O estudo utilizou o modelo experimental inteiramente ao acaso com 3 repetições e foi conduzido por 25 dias. Os alevinos foram distribuídos em tanques circulares de fibra de vidro de 150 L mantidos na escuridão e dotados de aeração mecânica, filtro biológico e renovação de água, na densidade de 34 indivíduos/tanque. A sobrevivência foi menor nos extremos testados (T1 e T5). Maior crescimento em peso e em comprimento e melhor conversão alimentar foram obtidos com o aumento da concentração de oxigênio dissolvido. Os alevinos de jundiá apresentaram incremento em peso, mesmo na menor concentração de oxigênio dissolvido (T1), e T4 produziu os melhores efeitos sobre o desenvolvimento

O objetivo deste estudo foi avaliar a sobrevivência e o crescimento de larvas de surubim, Pseudoplatystoma corruscans , em cinco densidades de cultivo: 15, 35, 55, 75 e 95 larvas/L, distribuídas em um delineamento inteiramente ao acaso com três repetições. Utilizou-se água salinizada (5%) para o cultivo. As larvas foram mantidas em ambiente sem luz e alimentadas com náuplios de Artemia sp. na proporção de 500 náuplios/larva/dia. Ao final do experimento (10o dia), a sobrevivência apresentou tendência de redução com o aumento da densidade de estocagem, mas não se verificou relação entre o crescimento e a densidade. As concentrações de amônia não ionizada e de nitrito apresentaram variação diretamente proporcional ao aumento da densidade e podem ter influenciado a sobrevivência final. A maior sobrevivência (52,0 ± 9,3%) foi registrada em cultivo com 15 larvas/L, sendo que essa densidade não produziu efeito negativo sobre a qualidade da água.