Bucket of aquatic mob

Fish buckets / buckets of fish are a form of water bucket with a fish inside of them.

Obtaining
A fish bucket can be obtained by a water bucket on any fish mob. The fish bucket obtained will correspond to the fish picked up. In the Bedrock Edition, an empty bucket can also be used to obtain a fish bucket.

Usage
Pressing with a fish bucket will place a water source block, and spawn the corresponding fish back into the world, leaving an empty bucket in the player's inventory. For tropical fish buckets, the patterns and color of the tropical fish are remembered and stored in the bucket. Placing a fish bucket in the Nether will cause the fish mob to be spawned alone, flopping out of water.

Tropical fish buckets
Tropical fish also have assigned names which can be seen after capture, so that the buckets are given names like "Bucket of Plum Blockfish", "Bucket of Sky-Orange Snooper" or "Bucket of Orange-Lime Dasher". Their colors are mostly named according to the colored block names, though with a few exceptions:



The base color will come first, and if the pattern color is different, it will come after that. Lastly, the fish bucket will be given a name according to the shape and pattern of the fish:

A tropical fish bucket pulled out of the creative inventory will spawn randomly colored tropical fish when used.

Trivia

 * When a water bucket is transformed into a fish bucket, it will actually push the bucket texture down one pixel. According to Dinnerbone, Jappa says this is due to the "weight of the fish."
 * Tropical fish buckets will always have the texture of a clownfish bucket/bucket of orange-white kob, regardless of whatever fish is actually inside.