I don't think anything is wrong with the frog. There are no unusual spots or discoloration. It has an unusual pattern, probably an albino reticulated, if the eyes are black (the red eye in the photo makes it difficult to tell).

General signs of illness include:

  1. problems swimming, floating on surface
  2. weight loss
  3. bloating
  4. cottony tufts attached to skin
  5. hemorrhage
  6. excessive slime
  7. bite wounds
  8. cloudy eyes
  9. distended vent
  10. excessive shed

If the frog is eating well and swimming normally, it should be OK.