I don't think it matters whether it is made for a dog or a human. Just remember to look at the EPA and DHA levels in it. Sometimes, they are so low that you'd have to feed 10+ pills a day for a GSD.
Here is the dosage for EPA and DHA:
The Benefits of Fish Oil to Your Dog's Health - Whole Dog Journal Article
I use Iceland Pure Sardine and Anchovy because of the high levels of DHA and EPA for the cost.
ADCH Mikko (USDAA) SCH-B; (NADAC) EAC, EJC, TN-E, TG-E, VerO; (AKC) NAJ, CGC; (NACSW) NW1 - 9 year old GSD