The effects of temperature manipulation, addition of sperm solution, and exposure to alkalized pH and/or hydrogen peroxide (H₂O₂) as possible spawning inducers in laboratory-conditioned and unconditioned adults of the yellow clam (Amarilladesma mactroides) were evaluated. In three trials, clams were laboratory-conditioned for 14 days and exposed to thermal shocks (from 20 °C to 23–29 °C), while clams from three additional trials were not conditioned but acclimatized for 45 min before spawning induction. Although conditioning advanced gonad maturity and increased the condition factor, none of the thermal treatments triggered spawning in these first trials. Histological analysis indicated that the gonads of conditioned clams were not mature. Alternatively, unfertilized and fertilized eggs, and larvae were observed after unconditioned clams were induced to spawn. The gonads of unconditioned clams were in an advanced stage of maturity. Exposure to temperature shocks, alone or in combination with the addition of sperm solution and with H₂O₂, resulted in spawning. Clams exposed to H₂O₂ kept their valves closed and had a high mortality rate. Temperature manipulation is the most promising stimulus to induce spawning in A. mactroides. As the success of conditioning depends on the stage of gonadal development at the time of capture in the wild, a period longer than 14 days may be necessary.

This research aimed to evaluate the effect of biofloc technology on the intestinal morphometry, productive performance, and survival of juvenile Mugil cephalus. An 87-day investigation was conducted with two treatments, each with three replicates. Treatment one involved rearing juvenile M. cephalus in a biofloc system with a C/N ratio of 15:1, and treatment two involved rearing juvenile M. cephalus with a water exchange and no carbon addition. Ninety (90) juveniles of Mugil cephalus with an average weight of 117.36 ± 6.48 g were randomly distributed into six (6) circular plastic tanks of 250 L (fifteen fish per tank). At the end of the experiment, 10% of each experimental unit’s population was sacrificed for intestinal morphometry analysis. The productive performance was evaluated every 30 days by randomly sampling fish from each tank for biometric measurements, including the specific growth rate (SGR), feed conversion ratio (FCR), condition factor (K), and survival. No structural changes were observed in the intestinal mucosa. The fish reared in biofloc exhibited a similar gut morphometry (villus length and villus thickness) compared to the fish in the water exchange system. The biofloc system does not compromise the gut health of mullet. No significant differences (p > 0.05) were observed in the final weight, weight gain (WG), daily weight gain (DWG), specific growth rate (SGR), condition factor (K), and survival between the treatments evaluated. M. cephalus can be reared using biofloc technology, demonstrating significant water savings compared to water exchange systems.

The objective of this was to evaluate the ability of bioflocs to assimilate and transfer antioxidant compounds present in açaí Euterpe oleracea to juvenile Penaeus vannamei shrimp grown in a biofloc system. Juvenile shrimp were distributed into four treatment groups (control, 5, 20, and 80 mg açaí L⁻¹), containing 31 shrimps/tank (90 L), and cultivated for 30 days. Every 24 h throughout the experimental period, the respective açaí concentrations were added directly to the cultivation water. The bioflocs and hepatopancreas lost their antioxidant capacity with increasing concentrations of açaí; however, lipid damage was mitigated after treatment with 20 mg of açaí L⁻¹ (p < 0.05). The application of 20 mg açaí L⁻¹ increased the mean height and area of the middle intestinal microvilli (p < 0.05). Mortality and protein and lipid damage in shrimp muscle increased with daily administration of 80 mg açaí L⁻¹ (p < 0.05). It is concluded that the bioflocs were able to assimilate the antioxidants present in açaí and transfer them to the shrimp, and the administration of 20 mg açaí L⁻¹ presented the best performance, demonstrating the possibility of its application in the cultivation of P. vannamei in a biofloc system.

Broodstock conditioning involves maintaining adult animals in optimal environmental conditions to ensure that the largest number of breeders reach maturity. We evaluated the gonadal development and the occurrence of spawns in the yellow clam (Amarilladesma mactroides) and estimated the duration of conditioning that results in the highest maturity rate. Clams were kept buried in a 10 cm sand bed within Ø = 15 cm containers. A concentrate of Isochrysis galbana and Chaetoceros muelleri was supplied daily. Four conditioning periods (14, 28, 45 and 60 days) with four replicates were used. On the day of collection and at the end of each conditioning period, clams were induced to spawn with thermal shocks (16.7 °C to 26 °C) and sperm. The first spawns were observed on day 28, but only 50% of the males and 33% of the females were mature, and their mean oocyte diameter (36.33 µm) was smaller than the minimum (45–50 µm) considered for ready-to-spawn clams. However, on day 45, all males and females were mature (mean oocyte diameter = 45.14 µm) and 1102 × 10³ eggs were released. To ensure a high maturity rate, yellow clams should be conditioned in captivity for 45 days. Monitoring gonadal development in the wild to collect clams at advanced stages of gonadal development may be a less expensive strategy worth considering.

Darwin's genius was creative in nature, not academic success. He did not excel at school, where prizes were awarded to students skilled in writing verse in Greek or Latin, or in dealing with the difficulties of Euclidean geometry. Darwin's voyage around nearly the entire world aboard the Beagle, in addition to making scientific contributions, sparked humanistic reflections that led him to question, among other things, his religious beliefs. The procedures Darwin applied were useful for various areas of humanity, including the possibility of creating different species, for example, more resistant to disease or favoring a certain skin color, etc. These procedures, indirectly borrowed from Darwinism, were called agricultural Darwinism. This article analyzes why it took Darwin so long to publish this book and evaluates this scientific contribution in conservative Victorian England, as well as the technological transfer that was refined centuries later. What we can conclude is that Darwin demonstrated a brilliant mind, great intellectual audacity, and the ability to combine the best qualities of an observant naturalist, a philosophical theorist, and an experimentalist, and his concepts endure to this day, helping to generate better productive strategies, especially in the food sector.

As lesões coronarianas já foram relatadas em espécies de peixes anádromos, com características semelhantes às observadas em aterosclerose humana, mas não em peixes cultivados sem interferência de padrões reprodutivos. Objetivou-se descrever lesões coronarianas em beijupirá (Rachycentron canadum) criado em sistema offshore, em 54 exemplares coletados ao longo do cultivo de oito meses. Amostras de tecido cardíaco de alevinos e juvenis foram submetidas à análise histopatológica e à microscopia eletrônica de transmissão (MET), para visualização de lesões coronarianas, sendo as lâminas histológicas coradas pela técnica de hematoxilina-eosina, ácido periódico de Schiff, alcian blue e reticulina de Gomori. Exames realizados pela fotomicroscopia de luz evidenciaram lesões arteriais caracterizadas por hiperplasia das túnicas íntima e média de artérias coronárias em, respectivamente, 29,63% e 79,63% dos animais, com redução do lúmen arterial. Na MET, foram observadas alterações na estrutura das coronárias com espessamento do endotélio e membrana basal, proliferação de fibroblastos e fibras colágenas, com acúmulo de material lipídico subendotelial, resíduos celulares aderidos à membrana basal e vesículas pinocitóticas com presença de lisossomos isolados. Constatou-se que os peixes da espécie Rachycentron canadum criados em cativeiro desenvolvem lesão arterial do tipo crônica degenerativa inflamatória.