Lironeca vulgaris is a parasite that lives in the gills of many species of fish on the California coast, more specifically the Gulf of California. Both male and female live the chambers of gills of their host (Robinson 1982). Many of the organisms that become the host of Lironeca vulgaris are benthic or benthopelagic (Moser and Sakanari 1985). Benthic is the lowest level of the sea or lake. Benthopelagic fish live at the bottom of the sea but not completely on the bottom of the sea. These fish are at the edge of the benthic zone. The Lironeca vulgaris find hosts at the bottom of the seas or lake.

Map of Gulf of California.

Why does the Lironeca vulgaris not go for hosts that are more at the surface of the ocean? There are more fish up there and they get more nutrients. Well the reason for this is because the Lironeca vulgaris are not photopositive. This causes them to not swim towards the sunlight. Even though they like hosts in the benthic region, the color of the host is important to the Lironeca vulgaris for the reason that they are not photopositive. They swim under colored objects so they can hopefully find lightly colored hosts. This also explains why they are found in the benthic fishes (Moser and Sakanari 1985).

The Lironeca vulgaris will however infest on pelagic fishes if they have to. They prefer not to but they will if factors such as temperature, salinity and pressure could cause them to. They can be found in bays but there are more outside of the bay (Bennett 1993).