Cat food help!

Question
My 3&1/2 yr old cat Ninja has lost a lot of weight over the last month or two. I started to notice it about a month ago when he just seemed a bit lighter to me, and then gradually he had diarrhea off and on, and then the vomiting began. He was vomiting really bad for a few days (about 4-5 times a day!); I took him to the vet today (he's lost a pound and a half already, so I need a solution fast!) and they agree with me that they think it's a food allergy. The answer I need is about a new food to give him - the one I got when I suspected the allergy is a kitten formula, and since he's not a kitten I don't think this would be suitable for him (NOW brand Turkey with Duck), although this food seems to have stopped the vomiting for now. He was previously on BG brand Tuna; when I gave him a can of their tuna (I feed him dry food mainly, but try to give him wet every few days as well) he threw up like crazy that day, but gradually got better. He was okay when he had a can of beef - their wet food is meat and water, nothing else. As you can tell, I suspect an allergy to Tuna. I know he needs a new food, but I don't know what to give as I want to take fish out of his diet entirely but every cat food under the sun seems to have salmon meal, or oil, or tuna, or some other fish ingredient. I was wondering if you knew of any brands that aren't insanely overpriced that don't contain any fish ingredients that are nutritionally complete? I would like to give him a 'bird-only' diet if possible (vegetables and such are fine; I just would like for all the meat ingredients to be derived from birds). I run a small in-home day care, so I can't just start making my own cat food and such - convienience is a must. Some wet food suggestions would also be beneficial please and thanks. Sorry if this jumps around a bit, I just want to make sure I didn't miss any details that might help.  :)
Thank you for any help you can provide!

Answer
Hi Heather.  Unfortunately, the only food I know of off-hand that has no fish in it whatsoever is California Natural Chicken and Brown Rice formula.  Even those foods which claim to be chicken formulas almost always contain fish somewhere in the ingredients list, but not California Natural.  This is a good food in a decent price range (less expensive than BG but probably more expensive than average foods).  If you're unable to find Cal Nat, you may end up having to try a prescription diet that has no fish in it, and see if that helps him.

Canned foods can be very difficult to find without fish ingredients because fish makes them so palatable.  Even Cal Nat's chicken formula canned food his fish in it.  But Wellness offers canned formulas such as turkey, chicken, and beef & chicken that don't contain any fish in them.  Sadly, all their dry foods contain some kind of fish, so you may need to feed a combination of brands in order to get both canned food and dry food for him while still avoiding fish.

If the kitten food is working for him, there is no absolute hard and fast rule that he must not eat it.  Kitten food is generally more calorie dense and tends to have more fat.  For this reason, it can cause adult cats to put on unwanted weight.  However, if he's energetic and this doesn't seem to be a problem for him, kitten foods will meet all of his adult nutritional requirements.

Best of luck in your search!

Jessica