Wowtcg.com has the (first?) preview of the Purple Puffer pet!
From the screenshots, this companion looks like it will be quite large. And oddly enough, it remains in its bubble even when underwater lol. Silly fish, you can swim! Perhaps it suffers from mysophobia (fear of germs)? :P
Note: The Wowtcg page states that this pet is Bind on Equip, but Wowhead and MMO-Champion's database is listing it as Bind on Pick Up. It's unclear which is true, but in the past most TCG companions have been Bind on Pick Up. With the changes Blizzard is making to pets and especially PetStore and TCG redeemable ones, it's tough to say and we probably won't find out for sure until Patch 4.3 is released.
I can't wait to see this FIRST aquatic pet on live servers!