That is the conclusion reached in a new scientific paper published in the Asian Fisheries Society Journal, authored by an international group of eminent fish health scientists led by FAO expert Melba Bondad-Reantaso. The paper was written in response to general societal concern that aquatic animals might harbour the SARS-CoV-2 coronavirus and play a part in causing COVID-19 in humans. It was concluded that there is no evidence, and it is extremely unlikely, that SARS-CoV-2 can infect aquatic animals. Therefore these animals play no epidemiological role in spreading the disease to humans. Aquatic food animals and their products, like any other surfaces, may potentially become contaminated with SARS-CoV-2, especially when handled by people who are infected with the virus. Nevertheless, with proper food handling and sanitation, the likelihood of contamination of aquatic animals or their products with SARS-CoV-2 should be negligible.
The abstract and full text of the paper are available here https://www.asianfisheriessociety.org/publication/abstract.php?id=1291