I eat fish about 4 days a week (salmon and ahi tuna). i'm also trying to get pregnant. is it okay to eat this much fish until i get pregnant?

Probably too much: The only safe amount of fish during pregnancy is none. The FDA has guidelines about how much and what types of fish are more or less dangerous, depending on the amount of mercury the specific fish is thought to contain. Planning such a diet should occur before conception and in consultation with you OB. Generally, large fish with a long lifespan (e.g., tuna) have higher mercury levels.

Be careful: Current recommendations by the EPA suggest 8 - 12 oz of fish / week of the varieties with the least amounts of methyl mercury. Wild caught salmon is low in mercury.However tuna including ahi happens to be one of the highest fish containing mercury. Wild caught salmon happens to be one of the least contaminated. Farm raised salmon may contain pesticides and PCB which are problematic as well.