From http://stackoverflow.com/questions/5773878/nhibernate-using-tenant-specific-table-prefixes

nhibernate-using-tenant-specific-table-prefixes.cs

public class EntitytMap:ClassMap<Entity>
{
    public EntitytMap()
    {
        Table("TableName");
        Schema(Session.TenantName);
        Id(p => p.Id, "Id").GeneratedBy.Identity();
    }
}
//If you want to have each tenant in their own schema, this should work. If you want to keep the schema the same but have a prefix on the table, you could change to:

public class EntityMap:ClassMap<Entity>
{
     public EntityMap()
    {
        Table(Session.TenantPrefix + "TableName");
        Schema("SCHEMA");
        Id(p => p.Id, "Id").GeneratedBy.Identity();
    }
}