I used to keep track of what I spent on food then I came to the realization ( many years ago) that keeping live animals costs money, serious money. If you have to keep track of it, you probably shouldn't be keeping them. Sounds rough, I know, but think about it. You can control what you eat however the better foods that keep you healthy are not always the cheapest foods on the grocer's shelves. Do you not buy them due to price or to preference?
When I had my marine tanks, I used to make a weekly stop at the seafood market. About the third week I was there, the sales clerk asked me how I was eating all that food so fast? When I told her it was all for my fish, she nearly flopped over. LOL But I had some really nice looking, healthy fish in my tanks. When I had to break down my last tank due to a divorce and move, the fish in the tank were a Maculosis Angel that I had had for 8 years, a Black Saddleback Clownfish that I had had for 7 years, a firetail/ bicolor blenny that was 5 years and a zebra striped serpent starfish that I had for about 10 years. Was the food bill worth it? I think so
Now I'm breeding freshwater Angelfish so they need a good balanced diet to make good healthy babies. The only thing I do based on price is where can I get the food I need at the best price. (From which LFS
.) As I said, if I kept track of what I was spending on just food, I'd probably not be enjoying my hobby as much as I do