Fish (food)

Raw fish (raw cod) is a food item. Raw salmon is a rarer variant of raw fish. Clownfish is an even rarer variant of raw fish that cannot be cooked. Pufferfish is a highly poisonous variant of raw fish. Cooked fish (cooked cod)is a food item obtained by cooking raw fish. Cooked salmon is a food item obtained by cooking raw salmon.

Fishing
The most common way of obtaining any type of raw fish (and its variants) is fishing. The wait time of one being caught is decreased with the Lure enchantment and the chance of one being caught is slightly decreased with the Luck of the Sea enchantment (so named because it increases treasure, not fish)

Guardians
Guardians drop raw fish as a common drop. The fish will be cooked if killed while on fire.

Guardians and elder guardians also drop fish as a rare drop. This has a 60% chance of being raw fish, a 25% chance of being raw salmon, a 2% chance of being clownfish and a 13% chance of being pufferfish. The chance of getting a fish can be increased with looting, but the type of fish is not affected.

Polar Bears
Polar bears drop 0–2 raw fish when killed. This has a 75% chance of being raw fish and a 25% chance of being raw salmon. Polar bears do not drop clownfish or pufferfish. The fish will be raw even if the polar bear is on fire when killed.

Fish
Fish drop respective items upon death.

Trading
Fisherman villagers will sell 6 cooked fish for 6 raw fish and 1 emerald.

Food
Raw fish restores and 0.4 saturation. Cooked fish restores and 6 saturation. Raw salmon restores and 0.2 saturation. Cooked salmon restores and 9.6 saturation. Clownfish restores and 0.2 saturation. Pufferfish restores and 0.2 saturation, and inflicts  III for 15 seconds,  IV for 1 minute, and  II for 15 seconds.

Ocelots
Raw fish can be used to tame ocelots, get cats off of chests, beds, etc., breed cats, and make baby cats grow up faster by 10% of the remaining time. Raw salmon, clownfish and pufferfish will also work.

Trivia

 * In the Halloween Update, Notch said he would add fish as a sea creature; however, he had limited time, and was thus only able to add them as an item. However, they will be added in 1.13 update.
 * Raw fish most closely resembles white crappie or tilapia. However, the texture files and language text label them as cod. In 1.13, it's in-game name will be cod as well.
 * The consumption of pufferfish inflicting the player with nausea and poison is actually based on reality, as real pufferfish contain the extremely dangerous toxin Tetrodotoxin within their organs, especially their liver. Muscle tissue and blood only contain trace amounts. In East Asia, pufferfish are considered a delicacy known as fugu, as small parts of the fish are actually edible.
 * If this dish is prepared incorrectly, it can be lethal through respiratory paralysis. Therefore, any chef preparing fugu would have to have special licensing/certification to prepare this dish.