Dogs aren't hybrids in the same sense that a flowerhorn or bloodparrot it. Dogs are selectivly bred members of the same species. Canis lupus familiaris. Canis lupus being the wolf. There are a few dog breeds that are cross species (I recall a breed that has black-backed jackle in it) but most aren't. Where fish are concerned they can be compaired to goldfish and bettas. Selectivly bred members of the same species. Perhaps the most important thing to remeber is that fish hybrids can often survive and even reproduce in the wild. Dogs cannot, wild poodles would never become an established species and destroy the gene pool of wild dogs, though feral dogs can be a problem. Hybrid fish are also a lot more difficult to identify, unlike dogs where you almost always know what you're getting.
Oh Oh Here we go again, Its hybrid bashing time from the "I hate hybrids and they should all be banned but FH's are ok cause they are cool" purists