I have been reading The Metabolism Advantage by John Berardi and he reccomends 10 fish oil capsules a day. Currently I take 1 flax and 5 fish capsules every day. Should I up it to 10? I know that fish oil is great for you and almost everyone should be taking it but how many should I really take?

Between 2-6g combines EPA and DHA. That's about 8-12 for normal fish oil caps.

However, look on the back and see how much is a serving size and how much is in a single cap.

ditto on what cynic said. but 10caps is a good average number when specific serving size and EPA/DHA quantities aren't known.

Most caps are 1000mg, but some are 1200mg and I think they even make 1500mg.

also, flaxseed oil is, arguably, a lot less effective than fish oil. flaxseed contains ALA, which the body must convert into EPA and DHA. some people aren't very efficient at this...lacking good quantities of the enzymes that do it.
and in general its not an efficient process to begin with, something like 15-20% turnover. when you consider about half a fish oil cap is EPA and DHA (500mg), vs only getting 20% if it were flax (1000mg * 20% = 200mg), that's over 2x as much flaxseed oil needed to get the same fatty acids. which means over 2x as many fat calories needed...and that gets counter-intuitive pretty quick.

Both are polyunsaturated fats.

Fish oil contains DHA and EPA EFAs. Flax has ALA EFA. Both are good for increasing your poly unsat fat intake.