Jellyfish only spawn in coral reef biomes in groups of 4-5. Jellyfish come in colors that correspond to the color of the coral block they spawn closest to. Jellyfish will not spawn on dead coral. Their sizes range from 1 block to 2 blocks in length.
Each jellyfish has a color corresponding to the color the coral it spawns on, and are a little transparent. There is also a rare chance to find one on the top of the head of a drown.
*0-1 bottles of poison
Like every passive mob they will aimlessly wander around, but when they are attacked they will be boosted in the opposite direction of the threat (like a squid) and deal damage to the enemy on contact. When pushed by the tide onto the beach their tentacles are separated from the body leaving only the body on the shore, making it safe for the player to wear as a hat. This hat feature will despawn after 3 minecraft days to compensate for jellyfish rarity. Jellyfish can also be fished but have the rarity of a nametag when fishing. Also, any eggs found on beach will not hatch due to their inability to spawn in those conditions. It will die after 5 seconds.
Jellyfish cannot be attached to leads
Jellyfish cannot be picked up by boats.
Jellyfish are attacked by the following mobs:
Jellyfish will not follow players that have seagrass, instead the player has to get close to them and feed them. After two jelly fish are fed they will enter love mode and drop a random egg on a random coral block. They can re enter love mode after 3 minecraft days.
*Disclaimer* I was a little bit tired at the time of me typing this.