Just as title says. I'm not sure if I misread, but I went to the feats tab to check what I needed, and it said to acquire this pet. I went to the pet vendor and spent 400 source marks and no feat popped. Any help is appreciated, thank you.
Pets purchased from the Chang Tzu vendor don't give feats. You need to acquire it either as rare drop from content (in this case Atlantis: The Throne raid, that's where Atlantean Seahorse trinket can drop) or from broker/trade to unlock the feat. The feat description specifically says "Equip Rare Drop - Tier 2 or Tier 3". Tier 2 pets drop from regular content, Tier 3 drops from elite version.
Oh I guess I'll just eat that exorbitant fee we have the pleasure of paying for a mediocre tier 2 pet. Even after your explanation, I feel like we're splitting hairs with that verbage. I've only used the pet vendor once, specifically for this purpose. I bought it, and equipped it. No feat. I definitely feel bait and switched. But if that's the true design, thanks for clarification.
Unfortunately it is. Only dropped pet trinkets grant feats. If you just wanted the feat, then I'm sorry you wasted 400 source marks for nothing.