Birdfish

What's this? A Frogdog... A frog? Dog? Like a frog and a dog? Sure, next you'll tell me there's a Cattoad in the Cosmic Sea too.

— A drunkard reacting to a sailor's tale in a tavern.

These creatures who find habitat in the Cosmic Sea, and are the perfect example of the sheer randomness the sea can hold. Many birdfish are indeed part fish and part bird. For example, the Flying Cod is a cod with wings as fins.
However not all birdfish are part fish and part bird, as the Cosmic Sea is home to many amalgamations of wildlife. Examples of this are the Duckster, Girrat and the Dolpherpillar.

Birdfishing

Many sailors of the Cosmic Sea sail to catch birdfish. This is much like fishing or bird hunting in many 'ordinary' planes, like Atharia; however the risks are even greater, as the Cosmic Sea is full of dangers; like the Stegodragon and the Raptorcat.
Hunting birdfish, or just birdfishing, is done for both sport and for resource gathering. The Henhog, an animal part chicken, part pig; is a delicacy birdfish to be hunted for food in many cultures. Birdfishing is also used to harvest the scaled feathers of a birdfish to make, Birdfish Cloth; a fabric which is used for luxury clothing and sails for Planeship.

Birdfish Farms

What I farm is none of your business. Unless you're in the Planesails business, then we can talk.

— The birdfish farmer, Kherhik Cavetoe of Roxfair Birdfis Farm

There are birdfish which are captured and put into birdfish farms. This is a new process as a farm on the Roxfair Coast within Atharia controversally begun breeding the Aquimotos; a type of Birdfish which is farmed for its scaley feathers to make Birdfish Cloth.

Anti-Birdfishing

Ugh, you won't catch me eating that filth

— Someone who doesn't like to eat Birdfish.

There are those against this, like with many things of the world. However, those who are against this are so with, what they think, great reason. The Cosmic Sea is full of strange, wonderous and hazardous things. Not every Birdfish is safe to even go near, let alone to capture, harvest and to consume.
Many birdfish are poisonous even to be within proximity. Even though there are ways around this, there are still sceptics who think "what stays in the Cosmic Sea, must stay in the Cosmic Sea." Especially as there are now Birdfish farms being built.