Fish (mob)

Fish are common passive mobs found in oceans and rivers. They come in three variants: cod, salmon, and puffer fish.

Spawning
Cod spawn in regular, cold, and lukewarm oceans. Puffer fish spawn in lukewarm and warm oceans. Salmon spawn in frozen and cold oceans, and unlike the other two variants, can also spawn in rivers.

Drops
Fish drop their item form when killed. For example, when a cod is killed, it will drop one raw cod. In the case of cod and salmon, the drop will always be raw, even if the fish is killed while on fire.

Behavior
All three types of fish are not able to survive out of water. If outside of water, they will flop around for a while and eventually die of suffocation damage. When cod and salmon are outside of water, they will lay on their sides. Cod and salmon are passive in behavior.

Cod and salmon tend to swim in schools of fish (a maximum of nine cod or six salmon per school).

Puffer fish will puff up when approached by a player, going from unpuffed, then semi-puffed, to fully puffed. Puffer fish are passive mobs but going near one when fully puffed will inflict the player with seven seconds of, and touching them in their puffed form will deal some damage.

Salmon are able to jump up waterfalls.

Fish bucket
A fish bucket is a water bucket filled with fish.

To fill a water bucket with fish, it on a fish. a fish bucket will release the fish and water inside it.

The three variants of fish buckets correspond to the three variants of fish mobs. For example, a water bucket with a cod fish in it is called a cod bucket.

Trivia

 * Fish were also jokingly teased in the fake snapshot 12marc40awesome, along with coral and "fish blocks".
 * Despite its item form being named "Pufferfish", the bucket and spawn eggs refer to the respective mob as "Puffer fish", which is likely wrong.