Fish: Bad for cats and good for dogs?

I wasn't sure which section to put this in as it's about both dogs and cats but here it goes. I have been told several times, when looking at commercial cat foods, that fish is bad for cats and should not be fed as a part of a regular diet. I have never heard this for dogs however. on this forum I see many people feeding fish to their dogs but not to their cats which seems to follow that same trend. My question is, why is fish safe for dogs but not cats?

here are some links I've seen:
http://catnutrition.wordpress.com/2007/09/22/eight-strikes-against-fishy-feeding-for-cats/
http://www.littlebigcat.com/index.php?action=library&act=show&item=whyfishisdangerousforcats

It's early, so if this makes no sense, sorry:

Couple reasons I would think might make sesne are that cats are smaller - they can get addicted easier - can stop eating other things in favour of fish.

We feed fish. Salmon from a can sometimes, fresh haddock/trout/cod most recently, we have mackerel in the freezer for the cats (whole frozen).

I don't hesitate to feed them fresh fish. Maybe that's bad?

I don't know anything about dogs, but cats are descended from desert critters and don't biologically handle fish well. Each cat's tolerance is different, but "too much" fish can cause urinary tract infections, especially for male cats (with too much being one meal for some cats and a steady diet of fish for others).

I don't feed any fish here.

If you plan to feed your cat a lot of fish, make sure you cook it.

A regular diet of raw fish is bad for a cat's health. It's true that you never see a cat cooking a fish - but they don't generally succeed in catching many!

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Cat Food | Kitten Food

I don't think fish should be fed too often, raw or cooked.