The Scottish charity and four other viewers took issue with the brand's 'Everyday Amazing' TV campaign saying it misleadingly implied that Aldi's salmon were caught in the wild.
However, the regulator threw out the complaints noting that the spot, which was first shown back in September 2016, did not contain any express claims regarding the provenance of the German supermarket's salmon.
The ad (above) showed various fantastical scenarios, including an elderly women skydiving holding a roast chicken and a scene showing a man suspended from a height over a river holding a bottle of Aldi champagne. Another scene depicted a scuba diver reading a newspaper underwater who stated: "How's this for amazing? Aldi's Specially Selected Scottish Salmon is RSPCA assured," alongside on-screen text which backed up the claim.
The Save Our Seals Fund said viewers would understand from this that Aldi's salmon were caught in the wild rather than farmed, but the supermarket challenged this by pointing out there was no express claim about the way the fish were reared.
The watchdog agreed, saying that while the claim about the produce being RSPCA Assured didn't make it clear that the brand's salmon were farm-reared that the reference was unlikely to imply that Aldi's salmon were caught in the wild.
"Therefore concluded that the ad was not misleading," said the ASA.
Aldi fell foul of the ASA last summer after three of its Price Crunch' ads were banned.