Palaemon pandaliformis is a shrimp species considered as an important indicator of environmental condition. In this study, the toxicological effects of the mycogenic silver nanoparticles obtained using the fungus Aspergillus tubingensis (AgNP-AT) were evaluated on P. pandaliformis. The AgNP-AT were spherical and homogeneous in size. Compared with the untreated group, at 10 µM of the AgNP-AT there was a reduction of 60 and 87% of the oxygen consumption and ammonia excretion, respectively. In addition to the untreated group, silver nitrate (AgNO3) also used as a control, in concentrations at least 10 times lower than those of the AgNPs also reduced the oxygen consumption in 54 % and increased the ammonia excretion in 33 %, demonstrating its high toxicity. At 24, 48, 72 and 96 h, the AgNP-AT showed lethal concentrations (LC50) of 17.4, 14.4, 12.6 and 0.5 µM, while AgNO3 showed LC50 of 2.5, 1.0, 0.02 and 0.01 µM, respectively. For all groups exposed to AgNPs, the histological analysis showed that, in relation to the untreated group, there was a significant increase in the mean area of the shrimps’ gills, indicating hypertrophy. All the changes observed in the hepatopancreatic and gills tissue, mainly for AgNPs at the highest concentration of 10 µM, are described as reversible. The results indicated that the AgNP-AT toxicity to the shrimps increased according to the time of exposure. However, it is important to highlight that the AgNP-AT was less toxic than the AgNO3 to the shrimps, probably due to the presence of the protein coat in these AgNPs, which are able to control the release of Ag+ ions, avoiding high toxicity to the shrimps.