Welcome to the forum
.I guess if it were me and I was planning to eat the fish I wouldn't use that product without finding the MSDS and talking to the manufacturer. It does look like many of these use food grade dyes. It may be that it's not safe as a concentrate or it may just be that they didn't want to go through the rigamarole of testing the product for human consumption though. It might be worth calling the manufacturer or looking around to see if you can find one that claims it is safe. In the end it boils down to what you are comfortable with
Here's a site that talks about pond dye - https://www.platinumlakemanagement.com/blog/pond-dye-is-it-worth-the-money
Hope this helps.