The risk of infections by parasites such as fish lice, fungi ( " Saprolegnia " spp . ), intestinal worms ( such as nematodes or trematodes ), bacteria ( e . g ., " Yersinia " spp ., " Pseudomonas " spp . ), and protozoa ( such as dinoflagellates ) is similar to animal husbandry, especially at high population densities.
