Search

Background Bacterial infections are responsible of high economic losses in aquaculture. Mexican golden trout (Oncorhynchus chrysogaster) is a threatened native trout species that has been introduced in aquaculture both for species conservation and breeding for production and for which no studies of bacterial infections have been reported. Case presentation Fish from juvenile stages of Mexican golden trout showed an infectious outbreak in a farm in co-culture with rainbow trout (Oncorhynchus mykiss), showing external puntiform red lesions around the mouth and caudal pedunculus resembling furuncles by Aeromonas spp. and causing an accumulated mortality of 91%. Isolation and molecular identification of bacteria from lesions and internal organs showed the presence of Aeromonas bestiarum, Aeromonas sobria, Plesiomonas shigelloides and Ichthyobodo necator isolated from a single individual. All bacterial isolates were resistant to amoxicillin-clavulanic acid and cefazoline. P. shigelloides was resistant to third generation β-lactamics. Conclusions This is the first report of coinfection by Aeromonas bestiarum, Aeromonas sobria, Plesiomonas shigelloides and Ichthyobodo necator in an individual of Mexican golden trout in co-culture with rainbow trout. Resistance to β-lactams suggests the acquisition of genetic determinants from water contamination by human- or livestock-associated activities.

La biotecnología acuícola se basa en el conocimiento generado por investigaciones científicas multidisciplinarias aplicadas a la producción de organismos acuáticos. Las enfermedades infecciosas, el cambio climático y la sostenibilidad, son los principales retos actuales de la acuicultura. En este trabajo se hace una revisión de las posibles soluciones biotecnológicas a estos retos, a través del mejoramiento de las dietas, del uso de nuevas tecnologías de análisis, como son las ciencias ómicas y finalmente se discute la integración de especies nativas a la acuicultura. Todas estas actividades, con políticas públicas adecuadas, promoverán el desarrollo de una acuicultura más rentable, sostenible y acorde con las condiciones regionales, garantizando la seguridad alimentaria.

Teleost fish are the most diverse group of extant vertebrates and have varied digestive anatomical structures and strategies, suggesting they also possess an array of different host-microbiota interactions. Differences in fish gut microbiota have been shown to affect host development, the process of gut colonization, and the outcomes of gene-environment or immune system-microbiota interactions. There is generally a lack of studies on the digestive mechanisms and microbiota of agastric short-intestine fish however, meaning that we do not understand how changes in gut microbial diversity might influence the health of these types of fish. To help fill these gaps in knowledge, we decided to study the Mexican pike silverside (

An experiment was carried out to evaluate the effect of the use of a fish hydrolysate, CPSP Special-G™ (FH) and a soy protein isolate, SUPRO-590™ (SPI) in balanced diets, on growth performance, survival, body composition and nutrient digestibility in juvenile Pike Silverside, Chirostoma estor. Eight isonitrogenous diets (410 g kg−1): three with different substitution levels of FH (15, 30 and 45%), three with different substitution levels of SPI (15, 30 and 45%), a diet with a combination of both products (15%FH/15%SPI) and a control diet (0% FH, 0%SPI), were prepared. Juvenile fish (1376 ± 58 mg initial weight) were fed the eight diets three times a day, for eight weeks. Best growth was obtained in fish fed control diet and diets with an inclusion of 15% of both products alone or in combination (FH15, SPI15 and FH15/SPI15) (P 0.05) at the end of experiment. Dry matter, protein, lipid and energy digestibility (ADC) were influenced by ingredient type and inclusion level. There was a trend to decrease dry matter and protein ADC with increasing levels of SPI. Under the experimental conditions, the two products tested can be used separately or combined at inclusion levels up to 15%, without affecting fish growth and survival. Incorporation of 30 or 45% of either product could cause a detrimental effect on juvenile fish growth. This suggests that FH and SPI are viable protein sources at inclusion levels up to 15% in diets for juveniles of this species.

This study evaluated growth responses of white shrimp Litopenaeus vannamei by testing different combinations of Jatropha curcas kernel meal (JCK) and tilapia waste silage (FS) as dietary protein sources under laboratory and pond conditions. A reference diet (RD) based on fish meal was elaborated to contain 35% crude protein and 434 kcal/g; then, five isoproteic and isoenergetic experimental diets were formulated from RD with different FS/JCK proportions as follows: 75%FS/0%JCK; 56.25%FS/13.25%JCK; 26.5%FS/30.89%JCK; 18.75%FS/39.75%JCK; and 0%FS/53%JCK. For the laboratory trial, shrimp (2.90 g) were stocked at 10 m2 in an indoor recirculating system during 90 days. There were differences among the growth parameters of diets. Mean weight gain fluctuated from 6.71±0.61 g observed for the shrimp fed the 75%FS/ 0%JCK diet, to 9.70±0.61 g for the group fed the RD. The RD and 18.75%FS/39.75%JCK diet obtained the highest mean final weight (above 12 g), weight gain (above 9 g), and specific growth rate values (above 1.6%/day). Average final survival was 90.97%. The RD and 18.75%FS/39.75%JCK diets were used for the pond trial. Shrimp (0.49 g) were stocked at 10 m2 within 1-m3 cages into the pond for 35 days. Weight gain (3.47 g) and survival (93.33%) of shrimps were similar between the diets. Quadratic equations with the laboratory data indicated that the maximum responses for growth parameters correspond to FS and JKC inclusion levels in the range of 27.83 to 29.00%, and 32.25 to 33.64%, respectively. A combination of 18.75% FS/39.75%JCK meals as protein source is a potential alternative to effectively substitute FM in practical diets for L. vannamei at the studied ages under both laboratory and pond conditions.

A 7-week feeding trial was conducted to investigate the effects of replacing fish meal by autoclaved Salicornia bigelovii seed meal (SSM), supplemented with varying cholesterol levels, on feed intake, growth performance, body composition and survival of Nile tilapia Oreochromis niloticus fingerlings under laboratory conditions. SSM was tested at different inclusion levels (0, 25, 50 and 65 % of total protein), using different levels of cholesterol supplementation (0, 1, 2 and 2.6 %) in isonitrogenous (420 g Kg−1 DM crude protein) and isocaloric (18.52 MJ Kg−1 DM) fish meal–Soybean meal-based diets. Triplicate groups of fish (374 ± 15 mg, initial fresh body weight) were randomly stocked in 18 20-L plastic tanks at a stocking density of 20 fish per tank and were fed to satiation by hand five times a day, 7 days per week. Feed intake, growth performance and survival were significantly affected by the SSM inclusion level and the cholesterol supplementation. The lower growth performance of fish fed diets containing SSM without cholesterol is thought to result from the presence of saponins in the meal. When cholesterol is added, the saponin-induced toxicity is ameliorated, which is evident from growth and survival responses, up to 50 % of SSM protein inclusion. At the highest level of SSM inclusion (65 %), growth and survival were very poor, despite the addition of cholesterol. The results of the present work suggest that autoclaved SSM can partially substitute fish protein in diets for O. niloticus fingerlings at levels up to 50 % of the dietary protein if 2 % cholesterol is added in fish meal–SBM-based diets.

The genus Chirostoma (silversides) belongs to the family Atherinopsidae, which contains around 150 species, most of which are marine. However, Mexican silverside (Chirostoma estor) is one of the few representatives of freshwater atherinopsids and is only found in some lakes of the Mexican Central Plateau. However, studies have shown that C. estor has improved survival, growth, and development when cultured in water conditions with increased salinity. In addition, C. estor displays an unusual fatty acid composition for a freshwater fish with high docosahexaenoic acid (DHA)/ eicosapentaenoic acid (EPA) ratios. Freshwater and marine fish species display very different essential fatty acid metabolism and requirements, and so the present study investigated long-chain polyunsaturated fatty acid (LC-PUFA) biosynthesis to determine the capacity of C. estor for endogenous production of EPA and DHA, and the effect that salinity has on these pathways. Briefly, C. estor were maintained at three salinities (0, 5, and 15 ppt), and the metabolism of ¹⁴C-labeled 18:3n-3 was determined in isolated hepatocyte and enterocyte cells. The results showed that C. estor has the capacity for endogenous biosynthesis of LC-PUFA from 18-carbon fatty acid precursors, but that the pathway was essentially only active in saline conditions with virtually no activity in cells isolated from fish grown in freshwater. The activity of the LC-PUFA biosynthesis pathway was also higher in cells isolated from fish at 15 ppt compared with fish at 5 ppt. The activity was around fivefold higher in hepatocytes compared with enterocytes; although the majority of 18:3n-3 was converted to 18:4n-3 and 20:4n-3 in hepatocytes, the proportions of 18:3n-3 converted to EPA and DHA were higher in enterocytes. The data were consistent with the hypothesis that conversion of EPA to DHA could contribute, at least in part, to the generally high DHA/EPA ratios observed in the tissue lipids of C. estor.

The pike silverside has high aquaculture potential despite its slow growth. In this study, thyroxine (T4) concentrations (0.13, 1.3 and 13 nM), a control with no hormonal supplement and a negative control containing 4.5 mM methimazole (MMI) were tested to evaluate the growth of this species. Juveniles (0.2 g) were exposed by immersion to these treatments for 8 h every second day for120 days, and growth evaluations were performed monthly over the entire trial period. In addition, tissue samples from each treatment group were assayed for triiodothyronine (T3) and deiodinase type 2 (D2) activity. The survival rates in all T4 groups were high, and a signi¢cant increase in growth was observed (average of 58%). The MMI treatment caused an increase in mortality and a reduction in the ¢nal body weight compared with the control. T4 administration did not aiect the tissue levels of T3, and it decreased muscular D2 activity only after 30 days of exposure. These results demonstrated that low concentrations of T4 in the culture environment could improve the growth of this species without affecting tissue hormone levels. The technique may have useful applications for early-stage aquaculture of this and other economically important species.

The tilapia ¢shery in a large Mexican reservoir has declined in recent years, promoting eiorts to enhance stock quality in conjunction with feasibility studies for cage aquaculture. Spatial models to optimize cage location have been developed, incorporating aspects of topography, climate, hydrography, water quality and quantity, land use, infrastructure and socioeconomics. Three cage sizes were modelled, 5, 10 and 15 m diameter, for both high- and low-water levels. When full the, reservoir has a total area of 312 km 2 but a reduction in water level of 13 m was recorded between wet and dry seasons, signi¢cantly reducing the surface area available for cages to 265 km 2 . The results indicate a signi¢cant diierence in the availability of sites between seasons. For the small, medium and large cages at high water level, the areas classi¢ed as highly suitable or suitable were 151, 184 and 146 km 2 , respectively, while at low-water level these areas reduced to 113, 88 and 62 km 2 . Modelling this change in water level and the subsequent loss of available sites provide qualitative and quantitative guidelines for the development of aquaculture sites, their seasonal management and future monitoring, outcomes that can only be achieved using Geographical Information Systems and associated technologies.

Aquaculture continues to be the fastest growing animal production industry and this rate of expansion must continue if aquaculture is to satisfy global demand for fish products in the face of dwindling capture fisheries. The relationship between aquaculture and biodiversity is complex, with examples of positive and negative impacts having been reported. To enable this expansion while avoiding negative impacts from introductions of exotic species, the investigation of indigenous species becomes important and worthwhile.This paper establishes the background to development of new species for culture and describes the example of the Mexican silverside Menidia estor, which has for centuries been the principal species in an artesanal fishery in Lake Patzcuaro, Mexico. The species is geographically isolated and is unique but is now endangered because of a range of factors including overfishing, environmental degradation and introduction of exotic species. Considerable advances have been made recently in developing a closed reproductive cycle, understanding feeding and small-scale on-growing technology for the species. Based on this, a Darwin Initiative programme was developed focused on technology transfer to implement small-scale pilot on-growing thus helping to conserve the species and to improve livelihoods. This has allowed successful pilot scale development of aquaculture for the species while at the same time addressing the objectives of the international Convention on Biodiversity.

The Mexican silverside, Menidia estor, is a species with great regional importance and with very high prices in local markets. Unfortunately, due to high ¢sheries pressure, environmental degradation and pollution, the species has become endangered. Recently, there has been much progress in the biotechnology of this species, aimed at its culture, and the present paper describes the advances in feeding and nutrition of those important ¢sh. M. estor is a stomachless, zooplantophagous ¢sh, which also occasionally feeds on small ¢sh and crustaceans in the adult stage. Studies on the digestive enzymatic activities show high proteolytic capacity and a late or diierent model of digestive maturation from that described for marine stomach ¢sh. Nutritional studies on M. estor have shown that juveniles have dietary requirements of about 400 g kg 1 protein and 80 mg kg 1 vitamin C. The upper level of dietary carbohydrate for good growth and survival for juveniles is about 150 g kg 1 . Based on the high docosahexaenoic acid (DHA) content in £esh when fed on diets low in DHA, it is believed that the species has the capacity to biosynthetize420-carbon fatty acids from 18-carbon fatty acids. The high levels of DHA in £esh makes this ¢sh a very signi¢cant potential component of human nutrition. Using these ¢ndings the ¢rst practical diets for commercial culture of the species have been developed.

Anaesthesia, sedation and transportation of the Atherinopsid, Menidia estor, were investigated using benzocaine, hypothermia and combinations of the two. The optimum dose rates of benzocaine for sedation of juvenile Chirostoma estor were 15 and 18 mg L−1. When hypothermia was used alone, stable sedation of C. estor was induced at 15 and 12°C, with no mortalities and full recovery after about 8 min. There was synergism when benzocaine and hypothermia were combined, with the optimal combination being at 15°C and 12 mg L−1 benzocaine. Successful transportation was conducted over 3.5 and 8.5 h using combined benzocaine and hypothermia. Aloe vera extract used in the transportation medium reduced scale loss. This work has, for the first time, defined a systematically derived system of safe, long distance, live transportation of this species and others of the genus Menidia.

Lipid classes and fatty acid levels were analyzed in freshly fertilized eggs, early and late embryo development, and freshly hatched larvae obtained from wild and captive silverside Chirostoma estor estor broodstock, as well as in plankton, Artemia, and pelleted feed. The concentration of triglycerides (TGs) and highly unsaturated fatty acids (HUFAs) in neutral lipid fraction significantly decreased during early development and especially after hatching, whereas phospholipids and HUFA in polar lipid fraction remained constant. These results indicate that TGs rather than PLs are used as energy sources and that all HUFAs [20:4n-6/arachidonic acid (ARA), 20:5n-3/eicosapentaenoic acid (EPA), and 22:6n-3/docosahexaenoic acid (DHA)] of polar lipids are selectively conserved during early development. High levels of DHA (30%, on average, of total fatty acids) and low levels of EPA (4%) were observed in eggs, embryos, and larvae and did not reflect the proportions of these fatty acids in food. Preferential accumulation of DHA from food consumed by broodstock, and then transference to eggs, was probably occurring. The main difference between eggs from both origins was a low level of ARA in eggs from captive fish (4% of total fatty acids) compared to wild fish (9%). This could be associated with a deficiency in the diet that is not compensated for by desaturation/elongation of 18:2n-6 and, possibly, with greater stress in captive fish. In any case, particular requirements of ARA should be determined to optimize the culture of C. estor.

The growth and survival of white fish (Chirostoma estor estor) larvae were measured at different temperatures ranging from 16.1 to 34 °C. A single camera video system was used for accurate measurement of length of larval and juvenile fish, which enabled growth experiments on delicate animals with minimal handling. Use of a length/weight relationship then enabled estimation of mass. When applied to C. estor estor, the error of the system was generally less than 0.5% for length, but increased to over 1% when the distance of the larva to the grids increased. The total practical error in estimation of biomass using the video method was −2.05% for dry weight, with a range from −7.1% to +4.1%. Over a number of experiments, the recorded mortality due to the measuring process was less than 1%, representing a dramatic advance on all previous attempts to work with Chirostoma. This simple method could have wider utility for fragile larvae such as marine fish. Larvae were fed ad libitum with Brachionus rubens rotifers and Artemia franciscana nauplii for 1 month. The results showed that the optimum temperature for specific growth rates (SGR) was 28 °C, although survival was only 18% at this temperature. The best survival (53%) was at temperatures of 22 and 25 °C. The best overall temperature for growth and survival was 25 °C.

This study tested the use of sunflower seed meal as a dietary protein replacement for fishmeal in practical diets for tilapia fingerlings. In order to determine the optimum substitution level for this species, sunflower seed meal was used to replace 10%, 20%, 30%, 40% and 50% of the fishmeal protein in diets containing 40% protein overall. During a 70-day feeding period, diets containing 10% and 20% plant protein provided the best growth and feeding efficiency results, with values statistically similar to those of the control diet based on fishmeal as the sole protein. The unitary feeding cost index showed the highest profit with diets containing 20% sunflower seed meal. Growth depletion observed with diets containing higher sunflower seed meal percentages is explained by increasing Phe and Met deficiencies, and high non-digestible fibre content. It was concluded that sunflower seed meal is a suitable feed ingredient for tilapia complete diets when it constitutes up to 20% of the dietary protein.

The growth and survival of Penaeus vannamei postlarvae was measured at temperatures of 20, 25, 30 and 35 °C and salinities of 20, 30, 35, 40 and 50%.. Groups of 30 animals were used in each combination of conditions, in triplicate. The results clearly show that juveniles of this species have their best survival between temperatures of 20 and 30 °C and salinities above 20%.. Best growth was obtained between temperatures of 25 and 35 °C, with little difference being noted among salinities. Survival and growth coincide best at around 28 to 30 °C and 33 to 40%.. Calculated overall production was shown to be best in these conditions. The results demonstrate a high coincidence between the experimentally determined optimum conditions for production and the prevailing conditions in the coastal environment from which the animals originated.

"El objetivo del presente estudio fue estimar parámetros de las curvas de crecimiento del peso y la longitud en el pez blanco Chirostoma estor (EE), el pez blanco pico negro Chirostoma promelas (PP) y de sus híbridos recíprocos (EP y PE) hasta los 300 días de edad a partir de un cruzamiento dialélico completo bajo condiciones de cultivo en Morelia, Michoacán, México. La longitud se midió mensualmente desde la eclosión, mientras que el peso se midió mensualmente a partir de los 120 días. Los números totales de observaciones (muestras) analizadas para longitud fueron 1006 (26), 771 (22), 513 (22) y 421 (21) para los grupos EP, PE, PP y EE, respectivamente. Los números totales de observaciones (muestras) analizadas para peso fueron 630 (16), 521 (14), 263 (13) y 256 (13) para los grupos EP, PE, PP y EE, respectivamente. Las curvas de crecimiento para peso y longitud se estimaron con modelos de regresión no lineal. El grupo EE alcanzó un peso estimado de 7.89 g a los 300 días de edad, 65% mayor que el de PP (4.78 g) y 57% mayor que el promedio de los híbridos (P < 0.01); EE tuvo una longitud de 9.31 cm (14%) mayor que PP (7.97 cm) y 13% mayor que la del promedio de los híbridos (P < 0.01). Los cuatro grupos, mostraron un crecimiento de tipo alométrico positivo con valores de 3.2 a 3.3 (P < 0.05). Los resultados de este estudio son las primeras estimaciones comparativas de las características de crecimiento hasta los 300 días de edad para estas especies y sus híbridos en cautiverio."

In experiments designed to demonstrate the effects of instantaneous changes in salinity, juveniles were able to resist abrupt changes from fresh water up to 15‰ salinity without mortality, and the median lethal salinity (MLS) was 24‰. In a growth trial of 12 weeks duration at salinities of 0, 5, 10, 20, 30 and 35‰, final body weight, weight gain, specific growth rate, food intake and food conversion ratios were always higher in saline environments than in fresh water although differences were not significant. The best growth was observed at 10 and 20‰, the optimum probably being between these concentrations. The fish is clearly euryhaline.

The morphometric relationships, standard length-weight, standard length-width and weight-width for Cichlasoma urophthalmus (Gunther) in the weight range 0.78-262g were: log10 weight =−4.35 + 2.95 × (log10 standard length); log10 width =−0.73 + 0 99 × (log10 Standard length) and log10 width = 0.74 + 0.33 × (log10, weight). Two box graders were designed and tested based on these data. The operation efficiency (expressed as a percentage of the sample used to test it) was 96.1 % and 95% for the two graders. Results indicated a tendency to undergrading (small fish detained by the bars) by the first grader and overgrading (large fish going between the bars) by the second, the latter as a result of the major variability in the body shape from fish as they grow. The results are satisfactory, and larger graders for commercial use could be constructed based on these relationships.

A simple trial is described to determine the effects of brown fish meal, solvent extracted soybean meal, raw wheat meal, raw starch and dextrin on diet digestibility in juveniles of the Mexican cichlid, Cichlasoma urophthalmus (Gumher). The effects of possible anti-nutrients in the feedstuffs used were assessed with the purpose of designing practical diets. The results did not show any effect attributable to anti-nutrients, but showed that high dietary fibre levels reduced digestibility. The carbohydrates of soybean meal were poorly digested compared with the other sources utilized. These results suggest that the substitution of fish meal by soybean meat and other plant proteins could be increased to reduce costs of practical diets for this species.

The feeding habits of the cichlid Cichlasoma urophthalmus were studied in a brackish-water lagoon in Yucatan Peninsula, Mexico, from spring 1985 to spring 1986. The strong mandibular, maxillary and pharyngeal teeth, and the short intestine strongly suggest that C. urophthalmus is primarily a carnivore. Subsequent gut contents analysis revealed that this species feeds principally on invertebrates throughout the year and that there were few differences between the five seasons studied. The algal material found in some stomachs may be consumed as a consequence of predation on small invertebrates, but the feeding structures and short intestine makes this species unable to digest vegetable materials efficiently. Differences with other cichlids used in aquaculture are discussed.

Instituto de Investigaciones Agropecuarias y Forestales. Maestría en Producción Agropecuaria The culture development of pike silverside (Chirostoma estor) is presently at a pilot scale and several important zootechnical aspects are still being developed. An identified problem is its apparent slow growth and the occurrence of deformities in grow-out stages. The present work evaluated the feeding rate and tank type over these phenomena. For this, 1200 three month C. estor juveniles were evenly distributed in 9 circular tanks (8,482 L ) and 3 half-pipe raceways (163 L ). The organisms were subjected o three different feeding ratio treatments (apparent satiety, ½ apparent satiety, and ¼ apparent satiety) and two type of tank treatments (circular tanks vs half-pipe raceways). Three biometric and X-ray sampling points were done across r the duration of the experiment in order to evaluate growth and asses the rate of deformities. Fish fed to apparent satiety and ½ apparent satiety showed the highest growth (mass/length) with no significant differences (p

Instituto de Investigaciones Agropecuarias y Forestales. Instituto de Investigaciones sobre los Recursos Naturales. Instituto de Investigaciones Químico Biológicas. Facultad de Biología. Facultad de Medicina Veterinaria y Zootecnia. Facultad de Químico Farmacobiología. Programa Institucional de Doctorado en Ciencias Biológicas The use of continuous lighting is an increasingly common practice in teleost aquaculture, however the molecular interplays that modulate the growth, the feeding and the sex determination in fish are not well understood. The aim of this work is analyze the biological responses under: a) Continuous lighting photoperiod (CL) and b) Control simulated photoperiod (CS), which were applied after egg fertilization until 12 weeks after hatching. At the end of the trial the sex ratios, biometrics, feeding, circadian hormones profiles and gene expression (qPCR and RNA-seq) analyses were performed. We observed 40% of males in CS vs 73.3% of males in CL (p?0.05). The qPCR analyses indicate that 64.29% of CL individuals had a higher expression tendency of sox9 (testicular differentiation) vs foxl2 (ovarian differentiation), comparing with 35.71% in CS (p>0.05). The gene expression of oxidative stress biomarkers (sod2 and ucp2) and stress response (gcr1), did not show statistical differences between treatments (p>0.05). However, the transcripts of enzymes against oxidative stress (cat and gsr) and the activation of stress axis (crf) shows overexpression in CL (p?0.05). The fish of CL had an overgrowth (mass 66.14% and length 17.95% vs CS) and better feed conversion ratio 1.618 vs 1.95 in CS (p?0.05). With no statistical differences in survival and condition factor (p>0.05). The transcriptomic De Novo assembly indicates the presence of 68,960 contains annotated in 43,314 proteins.. El uso del fotoperiodo de luz continua es común en la acuicultura de teleósteos, sin embargo, los mecanismos moleculares que modulan el crecimiento, la alimentación y la determinación sexual no son bien comprendidos. En este trabajo se analizan algunos elementos de respuesta en: a) Fotoperiodo de luz continua (CL) y b) Fotoperiodo simulado control (CS); aplicados desde la fertilización y hasta las 12 semanas de eclosión en Chirostoma estor. Al final del experimento se identificaron histológicamente las proporciones sexuales, además se obtuvieron las variables biométricas, de alimentación, perfiles de hormonas circadianas y análisis de expresión de genes por qPCR y secuenciación masiva RNA-seq. En CS se observó un 40% de machos vs CL con 73.3% de machos (p?0.05). Los análisis por qPCR indican que en CL el 64.29% de los individuos presentan una tendencia de mayor expresión de sox9 (diferenciación testicular) vs foxl2 (diferenciación ovárica), comparado con el 35.71% en CS (p>0.05). La expresión de genes asociados al estrés oxidativo (sod2 y ucp2) y la respuesta del eje de estrés (gcr1) no muestran diferencias significativas entre CS y CL (p>0.05). Los niveles transcripcionales de enzimas asociadas a la defensa ante el estrés oxidativo (cat y gsr) y en la activación del eje de estrés (crf) presentan diferencias significativas entre CL y CS (p?0.05). Los organismos de CL presentaron un mayor crecimiento (masa, 66.14% y longitud, 17.95%) vs CS y un mejor factor de conversión alimenticia (1.618 en CL vs 1.95 en CS) (p?0.05); sin diferencias significativas en la supervivencia, ni el factor de condición (p>0.05). Los perfiles de cortisol revelan diferencias significativas (p?0.05), pero no para la producción de melatonina (p>0.05) entre tratamientos. El análisis transcriptómico De Novo en C. estor, indica que 68,960 contigs se anotaron en 43,314 proteínas.

Instituto de Investigaciones Agropecuarias y Forestales. Facultad de Biología. Facultad de Medicina Veterinaria y Zootecnia. Facultad de Agrobiología. Facultad de Químico Farmacobiología. Programa Institucional de Maestría en Ciencias Biológicas Diseases caused by parasites in aquaculture cause significant economic damage in this industry. In fact, the economic cost of protistan parasites to global fish culture plays a critical role in the aquaculture production, because there is a lack of control and management of infestations. The assessment in vitro of the effect of antiprotozoal compounds in fish is difficult, due to the life cycle of parasites in the laboratory is complicated. However, due to the easy culture of the ciliated protozoan Tetrahymena, this organism can be used like a biological model. Nanotherapy is a new discipline that promises to be broad-spectrum for the development of "smart" drugs to specific pathogens. In the present study, the in vitro toxicity of the silver nanoparticles synthesized by Argovit™ and the University of Texas at San Antonio (UTSA) were evaluated for the first time against Tetrahymena sp. like potential technology for the control of ectoparasite infestations caused by ciliated protozoan in fish culture. In this research, the aseptic culture of Tetrahymena sp. was obtained. The ciliate was isolated and the genus of the species confirmed by morphological and molecular methods, the later using the gen 18s with 95% accuracy. The median lethal concentration (LC50) for NpsAg Argovit™ in Tetrahymena sp. was 2501 ng/L at 15 minutes until 796 ng/L at 60 minutes, while the LC50 for NPsAg UTSA was 4 and 1 ng/L at the 15 min and 60 min respectively. The median lethal times were 54 and 8 min at 900 and 3000 ng/L respectively by the NpsAg Argovit™ and 55 and 2 min at 1 and 11 ng/L by the NpsAg UTSA. The lethal concentrations (CL100) were 3300 y 10.6 ng/L for NpsAg Argovit™ and UTSA at 15 and 60 min respectively. The NpsAg caused rupture of membrane and apoptosis in the cell. En acuicultura el problema de las enfermedades parasitarias constituye una de las principales causas de pérdidas económicas y dentro de éstas, el impacto de protozoarios parásitos a escala global en el cultivo de peces, juega un papel crítico en la productividad, ya que la mayoría de enfermedades no cuentan con medidas de control adecuadas. Una de las principales limitantes para la evaluación de antiprotozoarios en peces, es la dificultad para completar su ciclo de vida en el laboratorio. Sin embargo, el fácil cultivo del ciliado Tetrahymena posibilita su empleo como modelo biológico. La nanoterapéutica es una nueva disciplina que promete ser de amplio espectro para el desarrollo de fármacos “inteligentes” a patógenos específicos. En el presente estudio se evaluó por primera vez la toxicidad de las nanopartículas de plata sintetizadas por Argovit™ y la Universidad de Texas (UTSA) sobre Tetrahymena sp. como potencial en el control de infestaciones por ectoparásitos ciliados en peces de cultivo. Con el presente trabajo, se obtuvo un cultivo aséptico de ciliados del género Tetrahymena identificado morfológicamente y confirmado molecularmente con el gen 18 s para un 95% de identidad. La concentración letal media (LC50) de Tetrahymena sp. a las NpsAg Argovit™ fluctuó desde 2501 ng/L a los 15 min hasta 796 ng/L a los 60 min., mientras que para las NPsAg UTSA fue entre 4 y 1 ng/L a los 15 y 60 min respectivamente. Los tiempos letales medios (TL50) variaron desde 54 a 8 min a 900 y 3000 ng/L respectivamente para las NpsAg Argovit™ y desde 55 a 2 min a 1 y 11 ng/L para las NpsAg UTSA. Las concentraciones letales (CL100) fueron 3300 y 10.6 ng/L para las NpsAg ArgovitTM y UTSA a los 15 y 60 min respectivamente. Ambas nanopartículas de plata ocasionaron ruptura de la membrana celular y apoptosis.

Instituto de Investigaciones Agropecuarias y Forestales. Facultad de Biología. Facultad de Medicina Veterinaria y Zootecnia. Facultad de Agrobiología. Facultad de Químico Farmacobiología. Programa Institucional de Maestría en Ciencias Biológicas The fish larviculture is based primarily on live feed (rotifers, copepods and artemia nauplii), which increases the production costs. It is necessary to develop proper microdiets in order to replace live feeds. Microdiets are specific feeds with a standard quality, easy handle and storage, which can provide the nutrients needed for proper growth and high survival of fish larvae. The aim of this study was to develop a microdiet as first feed for Mexican silverside (Chirostoma estor) larvae. A pre-experiment was performed with newly-hatched larvae to compare the performance of larvae fed a commercial microdiet (Otohime A1®) and larvae fed rotifers (Brachionus plicatillis), up to 30 days post-hatching (dph). The results show that C. estor larvae can consume microdiets since hatching. Based on these results, a first experiment was performed to determine the minimum weaning time for C. estor larvae. During the experiment, the performance of newly-hatched larvae was evaluated with four different feeding treatments, one in which larvae were fed only with rotifers until 30 dph, other in which larvae were fed only with Otohime A1® since hatching, and the other two, in which larvae were fed the first days after hatching with rotifers (B. plicatillis) and weaned at 5 and 10 dph with Otohime A1®. The results showed that the best time for weaning larvae was 10 dph, obtaining similar survival and growth (p>0.05) than larvae fed only with rotifers. La larvicultura de peces está basada principalmente en alimentos vivos (rotíferos, copépodos y nauplios de artemia), lo que incrementa los costos de producción. Es necesario el desarrollo de microdietas apropiadas para larvas, que permitan prescindir del alimento vivo. Las microdietas son alimentos específicos con una calidad estándar, de fácil almacenamiento y manejo, que pueden proveer los nutrientes necesarios para un adecuado crecimiento y alta supervivencia de larvas de peces. El objetivo del presente estudio fue desarrollar una microdieta como primer alimento para larvas de pez blanco (Chirostoma estor). Para ello, se realizó un pre-experimento con larvas de 0 a 30 días post-eclosión (dpe), en donde se probaron dos tratamientos de alimentación, en uno las larvas fueron alimentadas con una microdieta comercial (Otohime A1®), mientras que en otro las larvas fueron alimentadas con rotíferos (Brachionus plicatillis). Los resultados mostraron que las larvas pueden consumir microdietas desde la eclosión. Con base en estos resultados, se realizó un primer experimento para determinar el tiempo mínimo de destete de larvas de C. estor, durante el cual se evaluó el desempeño de las larvas hasta los 30 dpe sometidas a cuatro tratamientos, un control en el que se alimentaron únicamente con rotífero, otro en que se alimentaron desde el día de la eclosión con Otohime A1® y otros dos en los que fueron alimentadas los primeros días con rotíferos (B. plicatillis) y posteriormente destetadas a los 5 y 10 dpe con Otohime A1®. Los resultados mostraron que el mejor tiempo para el destete de las larvas fue a los 10 dpe, obteniendo un crecimiento y supervivencia similar (p>0.05) a las que fueron alimentadas sólo con rotíferos.

Instituto de Investigaciones Agropecuarias y Forestales. Facultad de Biología. Facultad de Medicina Veterinaria y Zootecnia. Facultad de Agrobiología. Facultad de Químico Farmacobiología. Programa Institucional de Maestría en Ciencias Biológicas Nematodes are live feed with potential for aquaculture, due to their rapid rates of reproduction, wide range of small sizes, from less than 10 ?m up to 2 mm, and potential for enrichment (Brüggemann, 2012). Turbatrix aceti is a free-living nematode and can swim actively and remain suspended in the water column, being this advantageous aspect for its use as live food in aquatic systems. Growing media for the nematodes can be solid or liquid, being the last one more versatile. The nematode T. aceti may be kept in a liquid basic medium (BM) consisting of vinegar and apple. However growth of T. aceti can be improved by the formulation of an artificial diet (DA) that exceeds the MB and allows scaling in the nematode production for hatcheries. The pescado blanco Chirostoma estor, an endemic silverside from Lake of Pátzcuaro, located in the State of Michoacán and it is an ancestral food source for Purepechas and mestizo communities of that region. Due to the environmental degradation of the ecosystem, to its high demand and prices in the local and regional market, wild populations of this species have declined in the Lake (RNP, 2008). This status evidenced the need to learn about the basics for C. estor aquaculture, feeding preferences and habits, the influence of environmental factors on the development and survival, Larval feeding, weaning and balanced diets (Martinez-Palacios et al., 2002). One of the critical stages in the life cycle of fish is the larval stage because during this the resorption of the yolk sac and the on setting of autotrophy takes place (Hoffer and Nassir-Udinn, 1985;) Jones and Hude, 1986; Kolkovski et al., 1993; Watanabe and Kiron, 1994) larvae must have a surce of feed that provides them essential nutrients to meet all its energy requirements for growth and survival, as well as been atractive enough an in an appropriate size to be able to be consumed by the small-mouthed larvae. Los nematodos constituyen un alimento vivo con potencial, debido a sus rápidas tasas de reproducción, pequeño tamaño y posibilidad de enriquecimiento (Brüggemann, 2012). Turbatrix aceti es el único nemátodo que se mantiene suspendido en la columna de agua, siendo ventajoso para su utilización en sistemas acuáticos. Los medios para crecimiento de nemátodos pueden ser sólidos o líquidos. T. aceti puede ser mantenido en una dieta base (DB) líquida con vinagre y manzana. El crecimiento de T. aceti puede mejorar al formular una dieta artificial (DA) que permita su escalamiento. El pez blanco (Chirostoma estor) es una especie endémica al Lago de Pátzcuaro en el estado de Michoacán, y fuente alimenticia ancestral para las comunidades Purépechas de dicha región. Debido al deterioro ambiental, a su elevada demanda y precios en el mercado , las poblaciones silvestres de dicha especie han declinado (RNP, 2008). A partir de eso surge la necesidad de investigar aspectos básicos para la acuicultura de C. estor (Martínez-Palacios et al., 2002). Una etapa crítica en el ciclo de vida de los peces es la larvaria debido a que durante ésta se presenta la reabsorción del saco vitelino e inicio de la autotrofía (alimentación exógena) (Hoffer y Nassir-Udinn, 1985; Jones y Hude, 1986; Kolkovski et al., 1993; Watanabe y Kiron, 1994) Las larvas deben contar con un alimento que les provea los nutrientes esenciales para cubrir sus requerimientos energéticos para el crecimiento y supervivencia, así como un tamaño adecuado para ser consumido. En la acuicultura de C. estor, y similar a lo que sucede en los peces marinos, se presenta una baja supervivencia en las etapas tempranas de desarrollo (Martínez- Palacios, 2002).

Instituto de Investigaciones Agropecuarias y Forestales. Facultad de Biología. Facultad de Medicina Veterinaria y Zootecnia. Facultad de Agrobiología. Facultad de Químico Farmacobiología. Programa Institucional de Maestría en Ciencias Biológicas Chirostoma estor is an endangered freshwater atherinopsid endemic to central Mexico. In this work we investigated the prescence of temperature-dependent sex determination (TSD) mechanisms that could be applied as a biotechnological tool for sex control in the culture of this species. This information could be useful also as a bioindicator of anthropogenic or climate change effects on its reproduction. For this work gametes from three single pair broods were manually fertilized, immediately divided in three groups, and incubated at 14, 21, and 29ºC. These thermal treatments were continued through hatching until 30 days after hatching (dah). All groups were then transferred to 21ºC. About 40-60 fish per treatment were sampled at 90 dah and processed histologically to determine phenotypic sex ratios. Also to determine the onset of sexual histological differentiation at 21ºC we sampled 20 larvae each week from hatching to 30 dah. The proportions of males for the first brood were 67, 65 and 90% (p≤0.01), to second brood, 57, 55 and 64 % (p≥0.05), and to the third brood 48, 75 and 92%(p≤0.01); at 14, 21, and 29oC respectively. Thermal treatments applied from fertilization show a clear effect in biased phenotypic sex ratios in brood 1 and 3, wich translates to substantial differences in the response of each brood to temperature. The histological differentiation onset was determined at 30 dah showing presumptive testis and ovaries with presence of somatic and primordial germ cells and the opening of the primordial ovarian cavity. These results suggest that incubation at high temperatures during embryonic development can lead to male-biased sex ratios in this species. The effects of lower and medium temperatures were not so clear, suggesting a mixture of genotypic and TSD mechanisms in C. estor as in other atherinopsids. Moreover, the histological differentiation onset was observed around 30 dah and suggests that molecular differentiation occurs early in the first larvae stages, however more studies are required to clarify the gonadal development in this important species. El pez blanco de Pátzcuaro Chirostoma estor es una especie endémica en peligro de extinción con un alto valor social, económico, ambiental y cultural del altiplano Mexicano. El presente trabajo fue realizado con el fin de obtener información científica sobre la determinación sexual por temperatura (DST) en esta especie, este conocimiento puede aplicarse como una herramienta biotecnológica para el control de la proporción sexual fenotípica en un cultivo comercial, así como para evaluar los efectos del cambio climático y la influencia antropogénica sobre la reproducción del pez blanco en el medio natural. A partir de 3 parejas de reproductores se obtuvieron gametos sexuales que fueron manualmente fecundados, inmediatamente después se dividieron en tres grupos y se incubaron a 14, 21 y 29ºC. Estos tratamientos térmicos se continuaron hasta 30 días post eclosión (dpe), posteriormente todos los grupos fueron trasladados a 21ºC hasta los 90 dpe. Al finalizar el experimento 40-60 peces por tratamiento fueron muestreados y procesados histológicamente para evaluar la proporción sexual fenotípica. Para determinar el inicio de la diferenciación sexual histológica a los 21ºC se muestrearon semanalmente 20 larvas desde la eclosión hasta 30 dpe. La proporción de machos para la primera progenie fueron 67, 65 y 90%(p≤0.01) para la segunda progenie, 57, 55 y 64% (p≥0.05) y la tercera progenie 48, 75 y 92%(p≤0.01) en 14, 21 y 29oC respectivamente. Los tratamientos térmicos aplicados desde la fertilización demuestran una influencia clara sobre la proporción sexual fenotípica para las parejas 1 y 3, por lo que la respuesta de cada progenie a la temperatura es significativamente diferente. El inicio de la diferenciación histológica fue determinado en el día 30 post eclosión con la presencia de testículos y ovarios en fase inicial de desarrollo, con la presencia de células germinales primordiales, somáticas y la apertura de la cavidad ovárica primordial.

El pez blanco Menidia estor (Jordan 1879) del Lago de Pátzcuaro, Michoacán, es una especie nativa y endémica del altiplano mexicano, perteneciente a la familia Atherinopsidae. Por su valor económico, cultural y nutricional es la especie de mayor importancia en la región, que por muchos años ha sido la base de la subsistencia del pueblo Purépecha. Debido a la intensa explotación y deterioro de su hábitat se le considera como una especie amenazada (Marez y Morales 2003), razón por la cual se vuelve necesaria la implementación de su cultivo. Durante los últimos diez años se han llevado a cabo esfuerzos de investigación (Martínez-Palacios et al. 2002, 2008) destinados a lograrlo exitosamente, obteniendo avances importantes. Sin embargo, una de las principales limitantes es su bajo desempeño en cuanto a crecimiento y supervivencia asociado a la utilización de dietas balanceadas. Diversas investigaciones han demostrado que los estudios sobre fisiología digestiva de las especies, contribuyen a generar dietas más adecuadas. Los estudios realizados sobre anatomía y bioquímica digestiva en el pez blanco (Toledo- Cuevas et al. 2007, Martínez-Palacios et al. 2008) sugieren una mayor importancia de la digestión citosólica sobre la luminal. Con base en esto, parece ser recomendable ofrecer un alimento que contenga péptidos pequeños y aminoácidos libres disponibles para su más fácil digestión y absorción. Una alternativa a esto es la inclusión de hidrolizados proteínicos. En este trabajo se utilizó como fuente proteínica al bagre armado Pterygoplichthys disjunctivus Weber 1981 o pez diablo, proveniente de la región del bajo Balsas en Michoacán. Esta es una especie pesquera sin actual valor comercial a la que se pretende encontrar alguna utilidad, tanto como alimento para consumo humano como animal, dada su abundancia y alta calidad nutricional. Se llevó a cabo un experimento para evaluar el crecimiento y la supervivencia de juveniles de pez blanco, alimentados con cuatro dietas isoproteínicas e isocalóricas, a base de proteína hidrolizada de bagre armado, y una testigo conteniendo proteína hidrolizada comercial de pescado. Los hidrolizados de bagre armado fueron a diferentes tiempos de digestión: 0, 15, 60 y 240 minutos, con el empleo de la enzima Protamex®, una proteasa comercial grado alimenticio.

Instituto de Investigaciones Agropecuarias y Forestales. Facultad de Biología. Facultad de Medicina Veterinaria y Zootecnia. Facultad de Agrobiología. Facultad de Químico Farmacobiología. Programa Institucional de Maestría en Ciencias Biológicas The morphology of orobranchial structures is key in the process and habits of fish feeding. Thus, according to the feeding habits, there may be marked structural differences between different species that reflect different food preferences. This work describes and compares the orobranchial structures of four species of Atherinopsid fish: the white fish of Pátzcuaro (Chirostoma estor), the white fish of Chapala (Chirostoma promelas), the Argentinian pejerrey (Odontesthes bonariensis) and Patagonian pejerrey (Odontesthes hatchery), and correlates the orobranquial structure and morphometry with existing information of gut contents and feeding habits. Our results show that C. estor presents a mouth in terminal position and gill structures that form a tight sieve (34.04 ? on average) that defines this species. On the other hand, C. promelas also presents a terminal mouth, however its morphological characteristics give it greater ability to consume larger size prey with respect to the other three species in relation to its size?. O. bonarioensis also features a terminal mouth, but crucially, its gill structures form a larger and open sieve (inter-branchial spaces 53.71 ? on average and the first branchiespinal arc of 5733 mm) than in C. estor, (branchiespínal of the first arc of 3.019 mm) therefore the ability of filtration is reduced in this O. bonariensis. In fact,its terminal mouth allows it, just as the c. promelas, to feed preferently on pelagic organisms. According to the position of the mouth, and morphological characteristics of their orobranchial structures, O. hatcheri can be considered as benthos predator and a species with lower filtration ability than C. estor and O. bonarioensis, but with more capacity than C. promelas. La morfología de las estructuras orobranquiales es clave en el proceso alimentario en peces. De acuerdo a los hábitos alimentarios, pueden presentarse marcadas diferencias estructurales entre las diferentes especies, las cuales reflejan preferencias alimenticias distintas. En el presente trabajo se describen y comparan las estructuras orobranquiales de cuatro especies de peces aterinópsidos: el pez blanco de Pátzcuaro (Chirostoma estor), el charal boca negra de Chapala (Chirostoma promelas), el pejerrey argentino (Odontesthes bonariensis) y el pejerrey patagónico (Odontesthes hatchery), y se relaciona la morfometría orobranquial y la información existente de contenido intestinal de las cuatro especies con sus hábitos alimentarios. Chirostoma estor presenta boca en posición terminal y sus estructuras branquiales forman una malla con espacios pequeños (34.04 ? en promedio) que hace evidente los hábitos filtradores de esta especie. Chirostoma promelas además de poseer la boca terminal, tiene características morfológicas que le confieren mayor habilidad para consumir organismos de mayor tamaño respecto a las otras tres especies (en relación su tamaño). La boca de Odontesthes bonarioensis también terminal, pero sus estructuras branquiales forman una malla de mayor tamaño y más abierta (espacios enterbranquiales de 53.71 ? en promedio y branquiespinas del primer arco de 5.733 mm) que C. estor, (branquiespínas del primer arco de 3.019 mm) por lo tanto la habilidad de filtración se ve reducida en esta especie. Su boca terminal le permite, al igual que a C. promelas, alimentarse de organismos pelágicos. De acuerdo a la posición de la boca, y a las características morfológicas de sus estructuras orobranquiales, O. hatcheri puede considerarse como predador de organismos del bentos y una especie con menor habilidad de filtración que C. estor y O. bonariensis, pero con mayor habilidad que C. promelas.

Instituto de Investigaciones sobre los Recursos Naturales. Maestría en Ciencias en Limnología y Acuicultura In the last decade it has generated much interest in the start of cultivation of whitefish Chirostoma estor estor. This work is a characterization for the production of larval and juvenile white fish, for a pilot commercial production of one million larvae and juveniles per year, research and design of the plant focused on the creation of a commercial operation cost- benefit applicable for growing this species. It was designed and evaluated a recirculation system for incubation and fingerling, composed of five channels (0.16 m3), a settling tank (0.16 m3), a biofilter (0.32 m3) and an aeration tank (0.16 m3). The experimental period was 10 days, was to evaluate the quality parameters of water in this period. The biofilter nitrification ammonium levels in control-N and nitrite-N with acceptable values ??(

Instituto de Investigaciones sobre los Recursos Naturales. Maestría en Ciencias en Limnología y Acuicultura The effect of the use of benzocaine and hypothermia and its combination as sedatives in juveniles of C. estor estor were evaluated. Eleven different concentrations of benzocaine were used: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30 and 40 mg / L; Establishing eleven treatments, with three replicates each and its control without anesthetic, in water with a salinity of 5 ‰. Observations were made in the following time period: 1, 2, 4, 8, 16, 32 and 64 minutes for each treatment. The hypothermia experiment was started at the ambient temperature of the water (23.8 ± 2.8 ° C) and then with reductions at 3 ° C intervals with the following relation: 21, 18, 15, 12 and 9 ° C; Establishing in total five treatments with three replicates each and its control at room temperature. Se evaluó el efecto del uso de la benzocaína e hipotermia y su combinación como sedantes en juveniles de C. estor estor. Se utilizaron once distintas concentraciones de benzocaína: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30 y 40 mg/L; estableciéndose once tratamientos, con tres réplicas cada uno y su testigo sin anestésico, en agua con una salinidad de 5‰. Se realizaron observaciones en el siguiente periodo de tiempo: 1, 2, 4, 8, 16, 32 y 64 minutos para cada tratamiento. El experimento de hipotermia se inició a la temperatura ambiente del agua (23.8±2.8°C) y posteriormente con reducciones a intervalos de 3°C con la siguiente relación: 21, 18, 15, 12 y 9°C; estableciéndose en total cinco tratamientos con tres réplicas cada uno y su testigo a temperatura ambiental.