Finicky Feline with Seafood Allergies?

Hello everyone! First off, I'm a new member of this site, but not new at using it's advice. I thought I'd finally create an account here since I'm in a bit of a dilemma. My cat is allergic to seafood. Now, I know many of the experts (including most of you on this site) don't recommend diets high in seafood anyway, but my boy likes to take it a step further. Salmon oil in any food messes with his stomach. (As do any of the fish oils, really.)

We had found one food that's been working brilliantly for almost two years now and, ironically, the company went out of business due to thousands of cases of salmonella poisoning. Now, he won't touch dry kibble again at all. I've tried food with fish oils extremely low down on the list and supplement his diet with canned food (wet food diets are a little too expensive for me) but he's ripping the place to shreds because he's starving without his old food!

He was on Canyon Creek Ranch Chicken and Brown Rice.
He loves his Nutro Max and Instinct canned foods but won't touch the kibble of either.
Also tried and disliked (due to tummy reactions):
Blue Buffalo (Normal, not Wilderness, but their formulation is similar enough)
Natural Balance
Royal Canin
Merrick
Nutro Natural Choice

He either starts throwing up soon after or gets runny stool.
I used to work at a pet store for years, so I know how to properly transition between dry foods and I also know he's not getting into anything else since these issues only arise when I change his diet. Also, he's slightly overweight. He was more overweight, but since his food's been changed, he's lost a bit of that. (Hasn't lost his activity levels, though!)

If you fed the Nutro chicken and brown rice diet... there's no fish oil in it whatsoever. That leads me to think that your guy has another allergy on top of the fish allergy. 

I would look into feeding a Limited Ingredient Diet. Nature's Variety Instinct Limited Ingredient Turkey looks like a good fit for your situation. Good protein, no fish, no grains. Fewer ingredients than other foods, it's meat, tapioca, peas and vitamins. Most of the other instinct kibbles contain fish in some form, this one does not. 

If you don't have access to this food locally (only one store near me sells it), then you can look into California Natural Cat & Kitten grain free food, which is a limited ingredient food. I fed it to my dogs several years ago and liked the results I got, until I found out that one of my dogs was allergic to rice. Now they have truly grain free varieties. So that might be an option for you.

I would avoid feeding food with rice or corn in it, as those are known allergens for cats too. 

If that doesn't work for you... there's always natural balance, which is not a great food, but it is a hypoallergenic food. 

My cat had the WORST reactions to Natural Balance than any other food so far! I do have access to Nature's Variety Instinct. I feed him the canned Venison, beef, rabbit, and lamb. I worked at a Petco for some time and when my store first got Instinct, I took some samples home (Zorro was on Royal Canin at the time and was hardly tolerating it enough for me to be spending $30 on it). I don't remember ever having the Turkey. He really liked the rabbit...of course, but that price was far too rich for my taste buds. I'll check for their Turkey LID when I go in today. They were on my list of the next brand to try since, at the time, I had mostly ruled them out for price and I'm making a bit more now.

As far as switching goes, I usually go a full ten days delicately bringing Zorro over. His stomach is so sensitive and Canyon Creek Ranch went out with no warning, it could be part of the reason he's not eating much dry food. I only had about two or three cups of it left when I went to buy more and learned they're wiped off the face of the earth.

The Limited Ingredient Diets are new to their product line, so that may be why you haven't seen them before. 

I don't like Natural Balance personally, it's low in protein and fat and pretty much everything that your pets need, but for some pets you feed what works. I know of more than one person with a dog or a cat with food allergies that are so bad, that Natural Balance is the only food they can feed. So, while it isn't my first choice for a food, if the allergies are bad enough, sometimes it's more important to get their digestion stable. NB isn't a great food, but sometimes, you work with what you've got. 

Most of my experience with food allergies is with dogs. Porter doesn't seem to be allergic to much of anything. He's a bit of a finicky eater though. He won't touch a chicken kibble, but he LOVES chicken, turkey, duck, beef, venison and lamb in his wet food and eats those like they're going out of style and he won't touch a fish based wet food. Weird, right? I'm going to rotate the canned foods that he likes, to keep him interested in them. If he's this picky now... I don't want him to get super picky on me later. He's elderly. I don't think it's good for an elderly cat to go off of their food. 

The problem I have found with NV, is that food switches must be done very slow. Most vets will tell you, take a week to ten days to transition. I take it at my pet's pace because every one has been different. I watch their stools. If they look loose, I back off on the new food for a day or two and then try to increase again. If they don't firm up, then I go back to the old food until I find something that agrees with their system. Switching Porter took about ten days, but my last rescue dog took over a month to get used to grain free kibble. She'd been fed a food that was really high in grains by her previous owner (Kirkland) so switching to grain free was a bit of a shock to her system. 

I feed Porter Orijen Six Fish for dry food and Wellness Core canned. He gets more of the canned than of the dry. I think you might have better luck avoiding fish in the food, if you stick with feeding a wet food.