Feeding tuna daily to my cat

Question
Hi Becky,  I have a young cat, 1.5 years old by the name of Blondie.  I been feeding her tuna daily for about 2 months.  I give her approximately 2 teaspoons mid morning as a snack.  Recently, I was reading that tuna is low in calcium. The injurious nature of fish is that it has too high a phosphorus level and may cause a vitamin E deficiency or yellow-fat disease and/or may increase susceptibility to rubber jaw, a form of osteoporosis.  Blondie does eat dry cat food twice a day and has healthy, regular bowel movements and urniation.  I am curious if this information should be regarded or disregarded. Blondie is a mix breed and shows color markings of a siamese, especially with her blue eyes, otherwise I dont know her breeding as she came to me a stray.  
Thank you for you time.  And Happy New Year!!  Linda  

Answer
Hi Linda,
I honestly do not know. I would think that the small amounts you are feeding would be ok, but to be sure, I would check with a veterinarian.  
I give my cats a very small amount of canned cat food in the mornings... I guess that's kinda the same thing. It might be a healthier way to go.
God Bless,
Becky