Most modern diets contain a significant amount of fat. Even if you did a ‘whole food plant based no oil’ diet, it would have fats from nuts and plants. Omega-3 supplements would be a bonus. Is there a specific amount of dietary fat per day that you are aiming for?
There is no healthy way to get your entire fat requirement from fish oil pills. Incredibly expensive and inefficient.
Just eat fatty fish like salmon mackerel and sardines.
Good to also get a BALANCED amount of Omega 6 from olive oil, seeds, nuts.