In case your pooch smells “fishy,” some of the reasons could be: either it needs its anal glands compressed or maybe there’s a tooth infection in its oral cavity.
If the former one, then you can try doing it yourself by putting on rubber gloves and inserting your finger into the animal’s rectum. You can turn to Youtube for some helpful hands-on videos teaching you how to do this right. Not the most pleasant procedure, honestly, but it is going to benefit your pooch’s wellbeing in the long run. In case you don’t feel comfortable performing the anal glands compression yourself, you can always ask your vet or a groomer for help who knows exactly how to go about it.
If a fishy smell is coming from an oral cavity, most likely it is due to the developing gingivitis caused by plaque and/or mouth ulcers. Also, a decaying tooth can give out this distinctive nasty odor as well.
To take care of this problem, you might need to bring your mutt to an animal care specialist to see what can be done (professional teeth cleaning, tooth extraction, polishing, etc.). All the dental hygiene steps can be very costly, so it is highly recommended to maintain your fur baby’s oral health by regular teeth brushing (at least 2 times a week).