Yes, it can.
We're almost more careful about how we use it for humans, as it then can make the distinction between platonic love/like for another person and romantic feelings, or the feelings a mother has for her child.
We do tend to reserve 'elsker' for stronger feelings of love/like, using it more sparingly than an American would do 'love', but this is not specific to animals.
This distinction is also becoming less and less clear among the younger generation - who are strongly influenced by the English language. They 'love/elsker' their new dress or phone just like an American teenage girl would, while this love for objects sounds a bit off to the older generations. All generations can use 'elsker/love' for food and actions as a stronger version of 'liker/like/enjoy'. "I love cake/swimming!", etc.
Seeing as fish can't live without water, using 'elsker' in this sentence sounds perfectly fine to my native ear. I would say that my cat 'elsker/loves' raw salmon or chicken meat, because he goes absolutely crazy over it, but that he 'liker/likes' his regular cat food. :)