Just use an algae-based omega-3 supplement. Eating algae is how fish build up omega-3 levels in their bodies anyway.

Just get an omega 3 supplement that has a good amount of DHA and EPA. There’s not as much evidence to support it as there is to support eating fish, but that’s more due to a dearth of research on the subject than because the evidence suggests it has no effect.

Unfortunately it tends to be more expensive. I have recs if you’re in the UK but not much use otherwise!

Should be, that's where the fish get it from.

Not sure where you are located, but here in the UK supermarkets (eg Tesco) sell vegan omega 3/6/9 capsules.

Seaweed :)

very worth it! seven years here with no negative health effects noticed; plus, you’re saving animal lives and helping sustain the planet.

natural sources for omega FAs include hemp hearts and pumpkin seeds.