Scielo RSS <![CDATA[Latin american journal of aquatic research]]> https://scielo.conicyt.cl/rss.php?pid=0718-560X20190002&lang=es vol. 47 num. 2 lang. es <![CDATA[SciELO Logo]]> https://scielo.conicyt.cl/img/en/fbpelogp.gif https://scielo.conicyt.cl <![CDATA[Bio-mitigation based on integrated multi-trophic aquaculture in temperate coastal waters: practice, assessment, and challenges]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X2019000200212&lng=es&nrm=iso&tlng=es ABSTRACT In general, aquaculture wastes from traditional aquatic organism cultivation rapidly deteriorate the water quality of the surrounding ecosystems, endangering animals living in the area. The integrated multi-trophic aquaculture (IMTA) system is a bio-mitigation strategy to alleviate the adverse impacts caused by aquafarming pollutants on the environment and aquatic species. This study provides an overview of the IMTA system, explains the interactive processes among the different trophic levels, summarizes the major practices being followed around the temperate coastal waters with a field case study in Japan, and discusses the assessment of IMTA bio-mitigation efficiency through experimental greatly dependent on the customs and market values in the local IMTA practice. Bio-mitigation efficiency acquired in a land-based experiment exhibits its limitation in approach and conducts a comprehensive analysis on the possibility of applying numerical models to evaluate IMTA effectiveness. The selection of a suitable candidate organism is estimating that in the same or different culture conditions with various biomasses of extractive species. However, in open water experiments, it is difficult to evaluate the bio-mitigation effect of extractive species because the initial biomass ratio (IBR) of the extractive to target species is too small. Alternatively, the possibility of applying existing numerical models to assess IMTA is relatively low. In conclusion, an optimally designed large-scale IMTA experiment is required, in which the IBR of the extractive to target species is adequately considered, and a full-scale IMTA model should be further improved with a database of individual-based submodels for IMTA candidate organisms. <![CDATA[Hsp70 function and polymorphism, its implications for mollusk aquaculture: a review]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X2019000200224&lng=es&nrm=iso&tlng=es ABSTRACT Hsp70 proteins are widely found through several species, and they are considered among the most conservative proteins in nature, in both their sequence and function. They play an important role in the response mechanism to several different kinds of stress such as temperature and pathogens among others. In some species, the variations in the sequence of the Hsp70 gene result in intra-specific differential expression, and therefore in differences in thermo-tolerance of individuals as well as other productive characteristics. The study of the potential impact of the Hsp70 gene polymorphisms represents a field of study that could greatly help the mollusk farming industry. <![CDATA[Dietary protein quality and proper protein to energy ratios: a bioeconomic approach in aquaculture feeding practices]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X2019000200232&lng=es&nrm=iso&tlng=es ABSTRACT Supplementing high levels of dietary crude protein in the absence of amino acid balance and enough energy in fish diets may results in reduced growth, improper feed intake and poor protein utilization efficiency coupled with unviable feed costs and adverse environmental effects due to high nitrogen excretion. It is necessary to improve the dietary protein quality to avoid unnecessary nitrogen excretion, and the use of protein as an energy source by fish, quality and determine proper dietary protein to energy (DP:DE) ratios in order to maximize protein utilization efficiency. It will help the aquaculture sector to obtain better growth response at a low-cost and without any adverse environmental effects. In the present article, we have deliberated in detail the previous and ongoing researches about protein research in fish nutrition. Besides, we have made a comparison between two so far commonly used methods in protein research, i.e., the graded supplementation and diet- dilution technique. According to the data presented here, is focusing on the formulation of balanced diets, the diet-dilution technique seems to be more accurate than the graded supplementation method. Thus, future studies should be focused on the use of diet-dilution technique along with proper dietary protein to energy ratios in order to formulate well-balanced diets. These attempts will significantly improve the protein and energy research in aquaculture nutrition. Moreover, feed industries will become able to formulate biologically balanced and environment-friendly diets at a low cost. <![CDATA[Functional feminization of the Mexican snook (<em>Centropomus poeyi</em>) using 17β-estradiol in the diet]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X2019000200240&lng=es&nrm=iso&tlng=es ABSTRACT The Mexican snook, Centropomus poeyi, supports an important fishery in southeastern Mexico. Due to its protandrous hermaphroditism, females may be especially sensitive to overfishing because they tend to be larger and selective removal has the potential to negatively affect natural populations, thus making urgent the need to contribute on management strategies for the species. The objective of this study was to produce batches of reproductive females at an early age and a small size by using 17β-estradiol (E2) in the diet. In two separate experiments, we fed fish 0, 10, 20, 30, 40, 50, or 60 mg of 17β-estradiol per kg of food for 60 days during gonadal differentiation. Fish fed with 50 and 60 mg of E2 per kg of food resulted in 100% feminization, while the control group (0 mg of E2) was 100% male. Three years after feminization, sex-reversed fish remained female, producing oocytes and were capable of spawning, while fish in the control group were ripe males with running milt. E2-treated groups were significantly larger (weight and length) than the control groups for up to six months after treatment, but the difference was undetectable at 300 days post-treatment. Survival was high in all treatments (100%). We obtained high percentages of functional females using dosages of 50 and 60 mg kg−1 of E2 for 60 days, with 80% of the induced fish spawning and producing fertilized eggs and larvae. The results obtained in this study provide opportunities for broodstock management and sex manipulation. <![CDATA[Effect of body size on the energetic physiology of the West Indian top shell <em>Cittarium pica</em> (Linnaeus, 1758)]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X2019000200251&lng=es&nrm=iso&tlng=es ABSTRACT Cittarium pica is an endangered Caribbean gastropod of ecological and economic importance. In order to provide the basis for the aquaculture development and/or population management of this species, the relationships among its body size and physiological variables associated with the energetic balance were assessed. Individual measurements of rates of egestion (ER), ingestion (IR), absorption (AR), oxygen consumption (OCR), ammonia excretion (UR), mucus production (MR), absorption efficiency (AE) and scope for growth (SFG), were carried out on specimens between 0.01 and 12.07 g of dry weight of the soft parts (DW) under controlled laboratory conditions. Most of the variables showed positive potential relationships with the DW of the animals (ER mg h−1 = 1.51 DW0.37, IR mg h−1 = 4.13 DW0.32, AR = 2.56 DW0.30, OCR mL O2 h−1 = 0.38 DW0.74, UR μg NH4 -N h−1 = 19.17 DW0.78, MR mg h−1 = 1.28 DW0.14 and SFG = 36.92 DW0.22). AE did not show any relationship with this variable. The large snails had faster input and output of energy compared to the small specimens, also having proportionally greater energetic expenditures, mucus production, and energetic balance. <![CDATA[Soybean and linseed oil in replacement of fish oil in diets for female lambari <em>Astyanax altiparanae</em> Garutti & Britski, 2000]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X2019000200260&lng=es&nrm=iso&tlng=es ABSTRACT This study aimed to evaluate the effect of different proportions of soybean and linseed oil to replace fish oil in diets for female lambari (Astyanax altiparanae). A completely randomized design with seven treatments and five replicates was used. The treatments consisted of a diet containing fish oil and six diets containing different proportions of soybean oil (S) and linseed oil (L), 10S/0L, 8S/2L, 6S/4L, 4S/6L, 2S/8L and 0S/10L. The fish that received the highest proportion of linseed oil (0S/10L) had the lowest crude lipid in their carcasses. The highest linolenic acid (18:3n3) concentrations were detected in the carcasses of fish fed diets with high proportions of linseed oil (4S/6L, 2S/8L, and 0S/10L). The highest n6/n3 ratios corresponded to the carcasses of fish fed diets containing the lowest proportions of linseed oil (10S/0L and 8S/2L). The highest levels of 20:5n3 (eicosapentaenoic acid [EPA]), 22:6n3 (docosahexaenoic acid [DHA]) and ZEPA+DHA occurred in fish fed diets containing fish oil. Among the fish that received diets with vegetable oils, the ZEPA+DHA was higher in the fish of the treatments 4S/6L, 2S/8L and 0S/10L. Diets supplemented with a 4S/6L proportion provide adequate deposition of the n3 fatty acids series in the lambari carcass. <![CDATA[New coral reef structures in a tropical coral reef system]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X2019000200270&lng=es&nrm=iso&tlng=es ABSTRACT A multibeam sonar combined with an Acoustic Doppler Current Profiler (ADCP) were used at the Veracruz Reef System (VRS), Gulf of Mexico, during the spawning period of August 2016 in order to elucidate plankton trajectories within the study area. The new high-resolution bathymetry provided the location of 50 coral reefs, 27 more reefs than known at the VRS. Most of those reefs are submerged reefs located at depths greater than 40 m. The total coral reef area of the VRS was calculated in 70.1557 km2. Only ~10% of the total area corresponds to submerged reefs. Forty-eight species were identified, seven more than known species at the VRS, 45 of the order of Escleractinia and 3 of the order of Anthoathecatae. Acropora prolifera, a hybrid, was also identified in most reefs. All species were observed in the emerged and submerged reefs. The distance at which the three local river discharges (Jamapa, La Antigua, and Actopan) brought sediments to the VRS was calculated. Those are inappropriate areas for coral settlement or development due to sediment transport and temperature and salinity fluctuation. Finally, light penetration was measured at 19 m depth near one reef structure during August 2016 suggesting that even during cloud coverage and rain periods there was a light bioavailability at the sampling point. <![CDATA[Stable isotopes as a method for analysis of the contribution of different dietary sources in the production of <em>Macrobrachium amazonicum</em>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X2019000200282&lng=es&nrm=iso&tlng=es ABSTRACT Macrobrachium amazonicum is the native freshwater prawn species with the greatest potential for captive production in Brazil. The stable isotope carbon and nitrogen technique (δ13C and δ15N) is efficient to determine the contribution of different food sources to a given organism. We used this technique to estimate the contribution of the food sources in the biomass gain of M. amazonicum. Fish fillets were used to determine the isotopic fractionation between juveniles of M. amazonicum and a standard food source. Juvenile M. amazonicum were submitted to four treatments with different food availability to determine their contributions; T1: without soil substrate and with feed supply; T2: without soil substrate and feed supply; T3: with soil substrate, feed supply and addition of an aquatic macrophyte (Elodea sp.); and, T4: with soil substrate, aquatic macrophytes and without feed supply. Periphyton, plankton and precipitated organic material were present in all treatments. The isotopic fractionation was 0.57 ± 0.07 (carbon) and 2.14 ± 0.18 (nitrogen). The prawn fed with ration presented growth 2.4 and 2.82 times higher in the treatments without substrate (T1) and with substrate and macrophytes (T3), respectively. The contribution of the food sources reinforces omnivore in prawn. The benthic organisms and feed supply were fundamental for the better growth performance of M. amazonicum. Estimating the effective contributions of food sources can help in developing diets more adequate for the species, increasing productivity, reducing costs and reducing the environmental impact of waste substances. <![CDATA[Environmental manipulation on <em>Astyanax altiparanae</em> out-of-season spawning]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X2019000200292&lng=es&nrm=iso&tlng=es ABSTRACT This study aimed to evaluate the effect of manipulating hours of light and water temperature in some important reproductive parameters for Astyanax altiparanae fish farming during winter. The experiment was conducted from July 3rd to August 28th 2013 (57 days), and two groups of 32 couples of fish (G1 and G2) were used. On G1, hours of light and water temperature were not controlled; on G2, otherwise, these variables were manipulated in order to achieve similar conditions to those observed in spring. Every 14 days, eight couples of each group were hormonally induced with carp pituitary gland extract, and eggs were collected after semi-natural spawning. The percentage of females from G2 that spawned was higher than G1 (81.25 vs. 9.38%), the same trend was observed for a number of eggs produced per female (G1: 2,976.57 ± 1,085.71; G2: 8,471.14 ± 860.08). The G2 ovaries presented a higher incidence of primary growth oocytes and post-ovulatory follicles whereas G1 ovaries had more atretic follicles. Economic analysis showed that operational profit from eggs and larvae production on G2 was higher than on G1, as well as the gross margin. In conclusion, the results showed that environmental manipulation might improve reproduction management practices extending eggs and larvae production during the natural non-breeding season. Further studies are necessary to determine more appropriate facilities to be used by farmers in large scale, as well as management protocols to ensure the survival of post-larvae. <![CDATA[Effect of rearing conditions on astaxanthin accumulation in the white shrimp <em>Penaeus vannamei</em> (Boone, 1931)]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X2019000200303&lng=es&nrm=iso&tlng=es ABSTRACT Astaxanthin is an essential micronutrient that regulates shrimp physiology, acting as a free radical scavenger, increasing stress resistance, and enhancing the immune response, improving growth and survival in farm-raised organisms. Despite this, accumulation of astaxanthin has not been evaluated regarding rearing conditions of shrimp. Thus, this study aimed to assess the effect of rearing conditions (extensive vs. hyperintensive) in the accumulation of astaxanthin in tissues of shrimp Penaeus vannamei, using wild juveniles as a reference of the levels of astaxanthin present in the natural environment. The main oxycarotenoid found was astaxanthin, which was mostly accumulated in hepatopancreas (&gt;90%) in esterified form, while mostly free astaxanthin was found in exoskeleton and muscle (&lt;60%). Comparing wild and reared shrimp, the content of esterified astaxanthin was significantly higher in the hepatopancreas of shrimp reared under extensive conditions (191.45 ± 23.08 μg g−1) followed by wild shrimp (144.08 ± 13.92 μg g−1), while low values (3 ± 1 μg g−1) were found in shrimp reared under hyper-intensive conditions. Astaxanthin levels found in farm-raised shrimp were not explained by commercial feeds, since no astaxanthin (only traces of its chemical precursor p-carotene), was found in the six different commercial feeds analyzed for rearing shrimp. Thus, the results may be explained by primary productivity (i.e., phytoplankton) that is consumed as natural food by shrimp in the ponds of farming systems, or by the effect of specific rearing conditions on the microbiota associated with carotenogenesis in the gut of shrimp. In any case, commercial feeds should fulfill all nutritional requirements for shrimp, particularly under stressful conditions as it occurs in hyper-intensive farming. <![CDATA[Apparent digestibility coefficients of selected protein ingredients for pirarucu <em>Arapaima gigas</em> (Teleostei: Osteoglossidae)]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X2019000200310&lng=es&nrm=iso&tlng=es ABSTRACT Apparent digestibility coefficients (ADCs) of nine protein ingredients were determined for pirarucu Arapaima gigas, a Neotropical fish species with great aquaculture potential in the Amazon. ADCs of crude protein, energy and dry matter were determined by feces sedimentation in cylindrical-conical tanks. Experimental diets were composed of 795 g kg−1 of the reference diet, 5 g kg−1 of chromic oxide and 200 g kg−1 of the following test ingredients: fish by-product meal, salmon by-product meal, poultry by-product meal, hydrolyzed feather meal, meat and bone meal, blood meal, soybean meal, corn gluten meal and corn gluten feed. Blood meal, meat and bone meal and corn gluten feed resulted in low ADCs for pirarucu, whereas corn gluten meal, poultry by-product meal and soybean meal were better digested, indicating that these ingredients may be potential protein sources in feed formulations for pirarucu. The other animal protein ingredients presented intermediate ADCs values and, together with blood meal and meat and bone meal, they demonstrate that the nutritional quality of the animal by-products tested could be improved, especially by enhancing the processing methods of this group of ingredients. <![CDATA[Cryptic fish associated with different substrates in two coastal reef communities of Colima, Mexico]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X2019000200318&lng=es&nrm=iso&tlng=es ABSTRACT It has been established that cryptic fish (CF) contribute to keeping the equilibrium of marine environments, and are also potential indicators of the environment. In the present study, ecological evaluations of CF-associated with reef communities exposed to high or low anthropogenic pressure off the coast of Colima, Mexico (La Boquita-LB, and Carrizales Bay-CA, respectively) were carried out. During 2014 a total of 16 surveys were carried out during winter-spring (WS), and eight surveys were carried out in summer-fall (SF). Three CF surveys were carried out in each reef community, covering a 180 m2 area; several ecological indices were calculated, and the benthic habitat was characterized. A total of 3,056 CF belonging to 23 species, 22 genera, and 15 families were recorded. The species Axoclinus lucillae, Acanthemblemaria macrospilus, Coralliozetus boehlkei, Ekemblemaria myersi, and Hippocampus ingens represented new records for CA and LB. The physiographic and topographic characteristics of the marine substrate were factors that significantly influenced the occurrence of CF, especially those with reduced mobility. There was higher CF richness and diversity during the SF. The species A. macrospilus, C. boehlkei, and E. myersi, associated with rocky environments with high sponge and macroalgae cover, were identified as potential bioindicators of degradation of the benthic habitat. The species Cirrhitichtys oxycechalus, A. macrospilus, Coryphopterus urospilus, and Elacatinus punticulatus were associated with coralline, crystalline, and relatively unperturbed environments. <![CDATA[Lipid requirement using different oil sources in Mayan cichlid <em>Cichlasoma urophthalmus</em> larvae (Percoidei: Cichlidae)]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X2019000200331&lng=es&nrm=iso&tlng=es ABSTRACT The effect of different lipid levels (10, 15, 20 and 25%) and oil sources (fish oil: FO and soybean lecithin oil: LO) on growth, survival, digestive enzymatic activity, gene expression acetyl CoA carboxylase (ACC1) and fatty acid synthase (FAS) of Mayan cichlid larvae Cichlasoma urophthalmus were evaluated by a bi-factorial design. The larvae were fed from hatching with eight different experimental isoproteic diets (45% protein) and a commercial diet for tilapia as a control diet. The results showed that larvae fed the LO15 diet had the highest growth in weight and total length and higher trypsin activity. The lowest values in FAS and ACC1 expression were obtained exclusively with the lipid type (soybean lecithin). It is concluded that the inclusion of soybean lecithin at a concentration of 15% allows the 100% replacement of fish oil in balanced feed for the culture of Mayan cichlid larvae. <![CDATA[Effect of stocking density on growth and survival of the prawn <em>Macrobrachium tenellum</em>, cultured in a recirculating aquaculture system]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X2019000200342&lng=es&nrm=iso&tlng=es ABSTRACT The stocking density of the freshwater prawn native to the Mexican Pacific coast, Macrobrachium tenellum, has not been evaluated in a recirculating aquaculture system. M. tenellum prawns with an average wet weight of 1.71 ± 0.11 g were reared for 60 days at three stocking densities (T1 = 10 ind m−2; T2 = 15 ind m−2; T3 = 20 ind m−2), in nine (1 m2) tanks connected to a recirculating aquaculture system inside a greenhouse. Average individual weight gain (AIWG), biomass weight gain (BWG), specific growth rate (SGR), food conversion ratio (FCR) and survival rate (SR) were determined. Stocking density affected the BWG and SR. The lowest BWG was observed at the highest density (T1, 20.70 ± 4.75 g m−2; T2, 20.75 ± 4.72 g m−2; T3, 11.31 ± 3.65 g m−2), although weight per area unit increased with densities. SR decreased with increasing density (T1, 77.77 ± 9.62%; T2, 59.25 ± 12.83%; T3, 44.44 ± 4.81%). Other parameters did not show a difference between densities, with a maximum average individual weight at T2 (5.41 ± 1.14 g). The overall results suggested that stocking density affected the productivity and survival but not the individual growth of juvenile M. tenellum prawns cultured in a recirculating aquaculture system. <![CDATA[Record of abundance, spatial distribution and gregarious behavior of invasive lionfish <em>Pterois</em> spp. (Scorpaeniformes: Scorpaenidae) in coral reefs of Banco Chinchorro Biosphere Reserve, southeastern Mexico]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X2019000200349&lng=es&nrm=iso&tlng=es ABSTRACT The lionfish (Pterois volitans, P. miles) is the first known species of marine fish to invade the Caribbean and Gulf of Mexico, and it is threatening the biodiversity of the region's coral reefs. Its success as an invasive species is due to its high predation and fertility, fast growth and lack of predators. Its first recorded appearance in Mexico was in 2009. Twenty-two sites were monitored around the reef of Banco Chinchorro Biosphere Reserve (BCBR), to estimate their abundance, during 2013. Densities from 0 to 333 ind ha−1 (97.6 ± 140.2 ind ha−1) and biomasses from 0 to 58.7 kg ha−1 (18.2 ± 29.9 kg ha−1) were recorded, the highest so far in the Mexican Caribbean. In addition, two lionfish distribution zones were detected: leeward reef (LR) and windward reef (WR). LR was 4.6 and 3.9 times higher in density and biomass than WR, respectively. The sizes found in the monitoring ranged from 5 to 40 cm of total length. Finally, a gregarious behavior was observed in 47.5% of the recorded fish. Our results suggest that to prevent the development of large reservoirs of lionfishes in the BCBR, management and control actions in areas of high lionfish abundance should be prioritized. <![CDATA[Arms regeneration in the squid <em>Lolliguncula panamensis</em> (Mollusca: Cephalopoda)]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X2019000200356&lng=es&nrm=iso&tlng=es ABSTRACT During two sampling trips carried out over the continental platform of Gulf of Tehuantepec, a total of 101 Lolliguncula panamensis Berry, 1911 were caught. Thirty mature specimens (19 females and 11 males) were found to have unusually short arms. Dorsal mantle length, arm's length, and body weight were measured from the fresh specimens. Evidence of regeneration was observed at different points along arms; these may have been the result of partial autonomies. In the injured arms, the surface of the arm's tip was wholly covered with skin. Fracture planes were found in our histological sections; the autotomized arms exhibited constricted muscle fibers in the longitudinal sections indicative of wound closing. The arms of the specimens observed were very similar to the regenerating arms of other squids. This study represents the first to report arms regeneration and hectocotylus in this squid wild-caught. These results suggest that Lolliguncula panamensis exhibit partial autotomy, and the ability to regenerate the arms. Additionally, each of the eight arms can do so, presumably during defensive interaction or mating. <![CDATA[Effect of different phosphorus concentrations on growth and biochemical composition of <em>Chaetoceros muelleri</em>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X2019000200361&lng=es&nrm=iso&tlng=es ABSTRACT Chaetoceros muelleri is one of the most widely used microalgae species in aquaculture in northwestern Mexico as food for fish and crustaceans. Its importance is due to its fast growth, nutritional quality and lipid accumulation under nutrient-limiting conditions. However, the biochemical and molecular mechanisms of uptake of phosphorus (P) limiting conditions for this species is still unknown. This study aimed to analyze the growth and biochemical composition of C muelleri in response to different phosphorus concentrations. Four treatments under different phosphorus conditions were used: control (72 μM P), excess (144 μM P) and two treatments with phosphorus limitation, limited A (18 μM P) and limited B (7 μM P). The highest cell concentration was observed in control and excess of P (&gt;3.4×106 cells mL−1). The highest dry mass concentration and chlorophyll-a content were found in control medium (72 μM P) whereas the highest total lipid (4.42%) was found in the lowest P-concentration medium (7 μM P). No significant differences were found in the total protein content, but we did find differences between the treatments with phosphorus limitation (7 and 18 μM P). <![CDATA[First record of <em>Trichodina centrostrigeata</em> Basson, Van As & Paperna, 1983 (Ciliophora: Trichodinidae) from <em>Oreochromis niloticus</em> (Linnaeus, 1758) cultured in southeastern Mexico]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X2019000200367&lng=es&nrm=iso&tlng=es ABSTRACT Nile tilapia Oreochromis niloticus is one of the most economically important freshwater fish cultivated worldwide. Despite its importance and being one of the cichlid fish most studied from a parasitological point of view in Mexico, there are few studies about the ectoparasite protozoa that infect them. In this study, a total of 240 juvenile individuals of O. niloticus from an experimental culture (in Tabasco, Mexico) were examined to detect the presence of trichodinid parasites. Trichodinid parasites were impregnated with silver nitrate and stained with Harris’ hematoxylin solution for taxonomic evaluation. A disc-shaped trichodinid with a body diameter of 38 ± 3.3 μm adhesive disc diameter of 34 ± 3.3 μm and a denticulate ring diameter of 19 ± 2.1 μm was found. Trichodina centrostrigeata has been previously reported having specificity for cypriniform species, but in the present study, the Nile tilapia was reported as a new fish host and southeastern Mexico as a new geographical distribution for this parasite. <![CDATA[Compelling palatability of protein hydrolysates for Nile tilapia juveniles]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X2019000200371&lng=es&nrm=iso&tlng=es ABSTRACT This study aimed at determining the compelling palatability of different protein hydrolysates for Nile tilapia juveniles (Oreochromis niloticus). Four isoproteic (30% crude protein) and isoenergetic (3,200 kcal kg−1) experimental diets were formulated, with a 5% inclusion level of poultry hydrolysate protein (PHF), or swine liver hydrolysate protein (PHS), or feather hydrolysate protein (PHP) and a control treatment containing 5% of fishmeal (FPE). Four juveniles (2.9 ± 0.01 g) were distributed in 10 L tanks and fed four times a day, and before each feeding event, diets were drawn. The same amount of pellets from each diet was offered, and feeding behaviors were recorded during three minutes for each feeding event, referred to the time of capture of the first pellet, number of pellet rejections, and number of approximations without capturing pellets and quantity of consumed pellets. A significant effect (P &lt; 0.05) was observed regarding a higher consumption of pellets and palatability index for PHF, followed by PHS, FPE, and PHP. Therefore, it was concluded that PHF provided the highest compelling palatability for Nile tilapia juveniles, by displaying a 10.82% increase of the palatability index, 17% of final feed consumption, and presented a rejection number 6.89 times lower than FPE. <![CDATA[Effect of medicinal plants on the survival of white shrimp (<em>Penaeus vannamei</em>) challenged with WSSV and <em>Vibrio parahaemolyticus</em>]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-560X2019000200377&lng=es&nrm=iso&tlng=es ABSTRACT Survival was investigated in Penaeus vannamei fed with powdered plants (PP: garlic, echinacea, ginger, and basil) and challenged with white spot syndrome virus (WSSV) and Vibrio parahaemolyticus by ingestion and immersion, respectively. PP was added to commercial feed at a concentration of 1, 2 and 4 g kg−1. The infection with both pathogens was made at the same time. Shrimp fed with PP (4 g kg feed−1) at different frequencies showed higher survival (96.7%) as compared to the positive control group not fed with PP (6.7%). WSSV prevalence in live and dead shrimp was similar in all treatments challenged with both pathogens varying from 33.3 to 55%. PP protects shrimp against WSSV and V. parahaemolyticus. Therefore, further research about the effect of PP is necessary for commercial shrimp farms.