The objective of this study was to assess zootechnical and physiological performance of Litopenaeus vannamei postlarvae (PL) reared in three environments (CW, clear water; B, biofloc; BS, biofloc with artificial substrates) at three stocking densities (300, 600, 900 PL/m³) for 8 weeks. At the end of experimentation, shrimp were subjected to hypoxia, and physiological response was again assessed. During rearing, low levels of total ammonia nitrogen, nitrite (NO₂^̄) and nitrate (NO₃^̄) were observed in B and BS for 600 and 900 PL/m³. For 300 PL/m³, a slight accumulation of NO₂^̄ and NO₃^̄ was detected. For the same stocking density, shrimp reared in B and BS showed significantly higher weights than those grown in CW, except for final weight. No significant differences were observed in survival. The use of biofloc and artificial substrates permitted doubling density from 300 to 600 PL/m³ without affecting growth, survival, feed conversion rate and obtaining twice the biomass. Shrimp grown in B and BS stored a surplus of glycogen and carbohydrates in their hepatopancreas, which probably gave them a better physiological capacity to counteract high‐stocking densities and hypoxia. A tendency of a higher adenylate energetic charge was observed in shrimp maintained in B and BS.

Environmental DNA (eDNA) offers a promising, non-invasive approach for monitoring infectious agents in aquaculture. While molecular techniques for detecting shrimp pathogens are well established in host tissues, there is a lack of standardized protocols for pathogen detection from environmental samples using conventional PCR. In this study, we developed and validated a universal conventional PCR protocol for monitoring DNA from major viral and bacterial shrimp pathogens within pond water and sediment samples. The method was applied to two commercial shrimp farms in Mexico, where eDNA was extracted from field-collected water and sediment. Using published primer sets, we successfully amplified DNA sequences corresponding to six key pathogens—Infectious hypodermal and hematopoietic necrosis virus (IHHNV), Baculovirus penaei (BP), Monodon baculovirus (MBV), Shrimp hemocyte iridescent virus (SHIV), Candidatus Hepatobacter penaei (NHP-B), and Acute hepatopancreatic necrosis disease (AHPND)-causing Vibrio spp.—in environmental samples. Sequencing of PCR amplicons confirmed 93–100% identity to previously reported pathogen strains, highlighting the method’s reliability. Pathogen detection rates varied by site, sample type, and date, with the percentage of positive samples ranging from 11.1% to 77.7%. Notably, this is the first report of SHIV DNA detection from environmental samples in the Americas, highlighting its value for pathogen surveillance even in the absence of documented outbreaks. This protocol offers a cost-effective and scalable tool for pathogen surveillance in shrimp aquaculture, enhancing early disease detection and contributing to improved biosecurity and risk assessment frameworks.

The potential of Panagrolaimus sp. nematode as a live prey was assessed in longfin yellowtail Seriola rivoliana larval rearing. Larvae were reared from 3-11 days post-hatching (dph) in a 2000 L tank and fed on copepods and rotifers. On 12 dph, larvae were transferred to eight 200 L tanks at a density of 12 larvae L-1 to start the feeding trial, consisting of two treatments (Artemia or nematodes) using four replicates each. Rotifers were offered on 12 dph with a "co-feeding" from 14 to 16 dph (rotifer/enriched Artemia or rotifer/nematode). Only Artemia or nematodes were supplied from 17 to 19 dph. Feeding incidence was 80-90% on 14 dph, but more larvae were capturing rotifers than Artemia or nematodes. Artemia consumption increased more than nematodes at 19 dph, though it was not significantly different. Significantly lower enterocyte and villus heights in the posterior intestine were observed at 19 dph in larvae fed on nematodes but only in enterocyte height in the anterior one. No significant differences were observed between treatments in total larval length and body depth on 16 dph, but a significantly higher total length in the nematode one was present on 19 dph. A significantly higher survival was observed in treatment Artemia compared to nematodes. These preliminary results showed a lower nutritional condition in larvae fed nematodes; however, technical improvements need to be performed to increase Panagrolaimus sp. availability to larvae in the water column.