<pre><strong>Background.</strong> In Mexico, the biology of <em>Procambarus</em> has been more studied than other cambarid species due to its diversity and potential use in aquaculture. Fecundity, egg development, and growth under laboratory conditions have been evaluated of the <em>Procambarus</em> (<em>Austrocambarus</em>) <em>llamasi</em>. The effect of density and sex ratio on the development and spawning of gonads and growth of juveniles fed different commercial agricultural and aquaculture feeds has also been studied. There are no records of epibionts infesting this crayfish. The primary objective of this study is to determine the infestation and epibiont identification rates of the Corixidae family and the damage caused to the crayfish.<strong> Methodology.</strong> To determine infestation indexes were calculated: the mean intensity (IM) is the average parasite species in infected organisms (MI = n. Total parasites / n. Infected hosts); abundance (AB) is the average number of parasites per host examined (AB = total number of parasites / n. hosts examined), and prevalence (P) indicates the percentage of organisms parasitized by a species of parasites (P = n .infested hosts / n. hosts examined x 100). <strong>Results.</strong> Of the shrimp analyzed, 76 were infested with 2655 aquatic insect eggs corresponding to 34.93 intensity; 18.18 abundance, and 52.05% prevalence. As far as crayfish sex, infestation occurred in 39% (n=30) of females and 61% (n=46) of males. The aquatic insect in this study belongs to the genus <em>Sigara</em> sp., being the only species registered in the crayfish. <strong>Implications.</strong> When the parasite egg settles near the crab eye region, it is likely to cause visual problems or partial blindness; on the other hand, it could cause a deterioration in the health of the populations of these crabs. <strong>Conclusion.</strong> The eggs located on the cuticular surface of the cephalothorax of <em>Procambarus</em><strong> </strong>(<em>Austrocambarus</em>) <em>llamasi</em> correspond to insect the genus<em> Sigara </em>sp. Half of the studied population of the crayfish is infested by this epibiont. According to the results obtained it was determined that the eggs on the shrimp’s cuticular surface cause cuticle damage due to cementation on its shell.  Eggs can also cause esthetic damage affecting marketing for human consumption and make shrimp overweight due to the egg mass. </pre>

Aplodinotus grunniens represent a crucial artisanal fishery in the Usumacinta River’s middle basin that generates food and a subsistence economy. This study aimed to create a model that best describes growth for A. grunniens and provides information on the growth of this poorly known  pecies from the Usumacinta River. Data collection was  carried out over one year through monthly sampling. A total of 447 specimens were collected from January to December 2017. Von Bertalanffy’s growth constants were calculated by separate sexes using linear fit and the non-linear  Levenberg-Marquardt method. Hotelling’s T-squared test showed that growth was significantly faster in females than males. The estimated age at first maturity was two years in males and three in females. Considering the age reported for A. grunniens in other studies, the age  determined in this study indicates that the population could be overexploited. Larger fish are more vulnerable to fishing pressure, mainly during their highest reproductive activity when they aggregate for spawning. More research is needed to evaluate the population status, catch per unit effort, distribution, and abundance of adults, juveniles, and larvae.