If you remove fish meal you remove part of the protein in your ration plus the other nutrients the fish meal provides.
Now you need to replace it with something else.
Making a ration involves a lot of research and math.
A big company will either have a nutritionist or consult one.
Like I said it is not easy. Also it is going to be hard to make it cheaper
than a company which produces 1000s of pounds of feed.
here is alink for pounds to kilograms
https://www.google.com/search?q=pou...1.69i57j0l9.7719j1j4&sourceid=chrome&ie=UTF-8
formulas to change from one weight measurement to another are on the internet.
Good luck on your project.