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Efeito da frequência alimentar sobre o crescimento do Lambari, Astyanax bimaculatus (Characiformes, Characidae)

2026-08-03T17:03:11Z

Título: Efeito da frequência alimentar sobre o crescimento do Lambari, Astyanax bimaculatus (Characiformes, Characidae) Abstact: Among the native species with zootechnical potential for aquaculture, the lambari, Astyanax bimaculatus, has stood out with desirable characteristics for cultivation, in addition to the growing commercial acceptance as food and live bait for sport fishing. Thus, studies regarding the ideal amount of food are necessary for a better zootechnical performance of the species. Thus, this research aimed to evaluate and describe the influence of food frequency on the growth of A. bimaculatus. For the development of the research, matrices of A.bimaculatus were captured in a fish farm in Maranhão and taken to the Laboratory of Reproduction of Aquatic Organisms - LARAQUA, these specimens after the adaptation process were submitted to hormonal induction using a synthetic hormone in doses consistent with their body weight, then couples were stored in a spawning system composed of 4 basins (20 liters each) with constant aeration of blowers, where the semi-induced spawning occurred. After hatching, the post-larvae were transferred to a nursery tank, where they underwent food training with commercial feed for a period of 20 days. Subsequently the fry were submitted to biometrics and transferred to the experimental units where they received the pre-established treatments. Water monitoring was performed weekly using a digital Aksoak 88 multi-parameter and colorimetric meters for nitrite and ammonia. The results showed that the natural food together with the commercial feed 45% CP significantly influenced the development of the fry, presenting good initial indexes of weight and length. The physical-chemical parameters of the water remained within acceptable standards for the species throughout the research, and the zootechnical indices showed linear growth in relation to the increase in food frequencies. It was concluded that the growth of A. bimaculatus is influenced by the feeding frequency. Considering the best weight gain, we can indicate that the fingerlings of A. bimaculatus can achieve the best zootechnical performance when fed four times a day. However, it is worth mentioning that the increase in food frequency favored a higher feed conversion, as well as a greater demand for labor, emphasizing the need for an evaluation of all productive activity.

Maturação da ostra do mangue (Crassostrea gasar) em laboratório sob diferentes condições de temperatura e salinidade

2026-08-03T14:17:13Z

Título: Maturação da ostra do mangue (Crassostrea gasar) em laboratório sob diferentes condições de temperatura e salinidade Abstact: Mollusks ranked third in global aquaculture production in 2016 and hold significant production potential in Brazil. The coastline of Maranhão features vast estuarine areas suitable for oyster farming; however, the industry faces obstacles such as a lack of seed stock—currently obtained solely from the wild—due to the absence of hatcheries producing seed for the mangrove oyster Crassostrea gasar in the North and Northeast regions. Gonadal maturation can be induced in the laboratory by manipulating water variables, such as salinity and temperature, which directly influence the reproduction of these organisms. This study aimed to evaluate the process of gonadal maturation under controlled laboratory temperatures and salinities. Two experiments were conducted to test four temperature conditions (Experiment 1: T1 constant 32°C; T2 constant 24°C; T3 varying from 32°C to 24°C; and T4 varying from 24°C to 32°C) and four salinity conditions (S1 constant 40; S2 constant 20; S3 varying from 40 to 20; and S4 varying from 20 to 40). The experiments took place in 12 L rectangular tanks (53 x 32.5 x 10 cm) set up within a recirculating system with constant water exchange, with 35 oysters stocked in each experimental unit. Feed was provided twice daily at a density of 10 x 10⁴ cells mL⁻¹. A significant prevalence of females over males was observed in both experiments, with hermaphroditism occurring in 0.5% of the broodstock only in the salinity experiment. Condition index (CI) results showed increased values at temperatures between 24°C and 26°C and a salinity of 20. Gonadal stages of C. gasar broodstock indicated high gamete maturation (stage IIIA) at temperatures between 24°C and 26°C and a salinity of 20. Increases in temperature and salinity favored gamete release (stages IIIB and IIID). The gonadal occupancy index (GOI) showed increased gamete occupancy within the gonad at temperatures between 24°C and 28°C; while salinity led to significant value fluctuations, the results were similar across all treatments, with an average of 45%. Our results revealed a maturation pattern for the mangrove oyster C. gasar, which is favored by temperatures between 24°C and 26°C and salinities between 20 and 25. Thus, lower salinities and temperatures—or maintaining these lower levels—promote increases in CI and GOI, whereas increases in these variables result in a higher proportion of developing oocytes and gamete release.

Estudos dos aspectos alimentares e reprodutivos do ariacó Lutjanus synagris (Linnaeus, 1758) (Perciformes: Lutjanidae) capturado na costa amazônica do Maranhão, Brasil

2026-02-25T16:26:00Z

Título: Estudos dos aspectos alimentares e reprodutivos do ariacó Lutjanus synagris (Linnaeus, 1758) (Perciformes: Lutjanidae) capturado na costa amazônica do Maranhão, Brasil Abstact: The feeding habit and aspects of the reproductive cycle of Lutjanus synagris were analyzed for one year (June 2018 to May 2019) based on 359 organisms acquired monthly through artisanal fishing, in a fishing area on the Amazon coast of Maranhenses, Brazil. The specimens were captured with a standard set of longline and gillnet type of sawmill type, stored in isothermal boxes and transported to the Laboratory of Fishery Biology - Biopesq, of the State University of Maranhão. Biometric data such as total length (LT), furcal length (FL) and standard length (SL), total weight (WT), gutted weight (GW), gonad mass (MG) were obtained. For the study of biological aspects, processing of the gonads was carried out and for the study of dietary aspects, an assessment and identification of stomach contents was made, classifying them at the lowest possible taxonomic level. Numerical and gravimetric methods were used to obtain the feed data. For the processing of the gonads, the samples went through specific protocols. The sexual proportion, the weight-length ratio, gonadosomatic index and condition factor, length of first maturation and temporal variations in the gonadal development of females and males were evaluated monthly and established. The environmental data - temperature and precipitation, were obtained through INMET - National Institute of Meteorology and NUGEO - Geoenvironmental Nucleus of the State University of Maranhão and related to feeding and reproduction regarding seasonality in the sample period. Throughout the sample period, fully filled stomachs were the least representative compared to the other replenishment classifications. In the quantification of stomachs 54 were empty due to regurgitation. The values of the degree of repletion were influenced by the sampled months (ANOVA, p<0.05). The diet presented a cumulative curve of 272 items, classified in 9 categories: crustaceans, mollusks, porifers, vegetables, vertebrates, annelids, fragments of fish and shrimp, unidentified organic matter (OMNI) and polymers. The identification of the items showed that decapod crustaceans were the most significant prey observed in the stomachs of L. synagris. The main food items were Brachyura and Carídeos. Reproductive results revealed a sex ratio of 1.40F:1M, with a favorable proportion for females in June and December. Females were predominant in the length class of 36.0 to 40.0 cm of LT and males of 32.0 to 36.0 cm of LT. The LWR presented an allometry coefficient less than three (b <3). The maturational aspects indicated five reproductive stages for males and females: immature, in development, capable of spawning, regression and regeneration. The species showed reproductive activity throughout the year and two reproductive peaks, one during the dry season, the other during the rainy season. The estimate of the average length of the first sexual maturity (L50) for grouped sexes was 26.16 cm 11 LT and can be considered a good indicator of a stock not yet explored, however, the knowledge of the reproductive characteristics of the species L. synagris can be used to define appropriate management and management policies for the species.

Avaliação da sanidade em cultivos de tilápia (Oreochromissp.): qualidade da água, alterações branquiais e identificação de espécies fúngicas

2026-02-10T19:09:26Z

Título: Avaliação da sanidade em cultivos de tilápia (Oreochromissp.): qualidade da água, alterações branquiais e identificação de espécies fúngicas Abstact: The objective of this work was to evaluate the health of tilapia (Oreochromis sp.) crops through water quality, gill alterations and identification of fungal species. The collections were carried out in the metropolitan areas of São José de Ribamar and Paço do Lumiar, in the city of São Luís, state of Maranhão, Brazil, Water and thirty fish were collected to analyze the gills in six fish farms, three in São José de Ribamar (P1, P2 and P3) and three in Paço do Lumiar (P4, P5 and P6). The producers were interviewed from a semi-structured questionnaire to investigate, in particular, the management and sanity of the fish. The parameters were: hydrogenation potential (pH), temperature, salinity, dissolved oxygen (O.D.), ammonia and nitrite in situ in fish farms. Microbiological analyzes for determination of the Most Likely Number (MPN) of total coliforms and Escherichia coli were performed using the Colilert method. The gills and fish skin samples were removed for analysis of histological lesions and fungal isolation. The gills were removed and fixed in 10% formalin for 48 hours and for the preparation of the slides, the samples passed through histological processing. Isolation of the fungi from fish gills and skins samples was done in agaroud dextrose agar medium plus clorafenicol. Histological changes were assessed by calculating the Histological Alteration Index (AHI). The AHI data were analyzed by Student's t-test. The values of temperature. O. D., salinity and nitrite obtained were considered within the recommended standards. The pH verified in P6 is considered potentially stressful to fish and, therefore, predisposing to pathologies. The ammonia in P2 is within the standard considered sublethal. In all fish farms evaluated, the presence of total coliforms with high values for the fish farms of São José de Ribamar was verified. The presence of E. colibacteria was verified in P1 indicating fecal contamination of nursery water by the flow of some source of domestic effluent directly into the nursery or the artesian well that supplies the fish culture. Histopathological analyzes performed on the gills indicated morphological alterations in all tissues analyzed. The lesions were: respiratory epithelial lining, lamellar epithelium hyperplasia, blood vessel congestion, lamellar fusion, dilation of the sinus and lamellar aneurysm. The AHI values indicated statistically significant differences between the lesions found in P3 and P4, P3 and P6. Isolation of fungi samples showed the growth of fungi of the genus Penicillium sp., Aspergillus sp. and Fusarium sp. fungi producing mycotoxins. These species are associated with inadequate processing and storage of feed. The occurrence of these fungi may be environmental or may be related to the use of contaminated feed in the farms. The presence of mycotoxins in food has been associated with several fish pathologies. It is worth mentioning that there must be high fungal counts in the diet to indicate the presence ofmycotoxins