MVC EF 5 - How to reference Model FK Properties?

@foreach (var item in Model) 
{
<tr>
  <td>@Html.DisplayFor(modelItem => item.Species.Name)</td>
...

<dt>@Html.DisplayNameFor(model => model.Species)</dt>
<dd>@Html.DisplayFor(model => model.Species)</dd>

public async Task<IActionResult> Index(int id)
        {
            var dataContext = _petRepository.GetByOwner(id).Include("Species.Taxonomy");
            return View(await dataContext.ToListAsync());
        }

public async Task<IActionResult> Details(int? id)
        {
            var pet = await _petRepository.GetByIdAsync(id.Value); // Cannot use .Include("Species.Taxonomy") here.

            return View(pet);
        }

Error    CS1061    'Task<Pet>' does not contain a definition for 'Include' and no accessible extension method 'Include' accepting a first argument of type 'Task<Pet>' could be found (are you missing a using directive or an assembly reference?)

public async Task<T> GetByIdAsync(int id)
        {
            return await _context.Set<T>().AsNoTracking().FirstOrDefaultAsync(e => e.Id == id);
        }