Isopod means similar footed.
Some groups are parasitic and some travel in large groups at night.
They prey on diseased or injured fish and also attack fish that have been caught in commercial nets. They develop embryos in a direct matter within the female brood pouch and emerge as juveniles. Isopods are egg laying, but have no larval stages. The young are brooded in the female pouch. Some females can carry about 20-30 eggs.