Fish hosts are determined by looking at both lab metamorphosis and natural infestations. Looking at both is necessary, as lab transformations from glochidia to juvenile may occur, but the mussel may not actually infect a particular species in a natural situation. Natural infestations may also be found, but glochidia will attach to almost any fish, including those that are not suitable hosts. Lab transformations involve isolating one particular fish species and introducing glochidia either into the fish tank or directly inoculating the fish gills with glochidia. Tanks are monitored and if juveniles are later found the fish species is considered a suitable host.

In lab trials, Villosa iris glochidia metamorphosed on the green sunfish, smallmouth bass, largemouth bass, Suwanee bass, spotted bass, striped shiner, streamline chub, mosquitofish, greenside darter, rainbow darter, bluebreast darter, blackside darter, and yellow perch.

Ecosystem Impact: parasite

Species Used as Host:

• green sunfish, Lepomis cyanellus 
• smallmouth bass, Micropterus dolomieu 
• largemouth bass, Micropterus salmoides 
• Suwanee bass, Micropterus notius 
• spotted bass, Micropterus punctulatus 
• striped shiner, Luxilus chrysocephalus 
• streamline chub, Erimystax dissimilis 
• mosquitofish, Gambusia marshi 
• greenside darter, Etheostoma blennioides 
• rainbow darter, Etheostoma caeruleum 
• bluebreast darter, Etheostoma camurum 
• blackside darter, Percina maculata 
• yellow perch, Perca flavescens