Fantasy "Shark" - The Tsarphin

This new mob would be how the Hoglin is to the pig. They are a cousin of the dolphin that instead of making you faster would make you slower (The Tsarphins Curse). It would try to attack you every 5 seconds by diving and biting towards you and would deal 4 hearts of damage without armour. The Tsarphin is a bigger dolphin that has one big fin on top. It has rough skin, is bigger, and is darker than the dolphin. It would have around 9 hearts of health.

If you gave the Tsarphin rotten flesh it would try to bring it back to its nest and you can follow it. The Tsarphin's nest would be kinda like a shipwreck in terms of loot. The nest would contain 5-10 Tsarphins. 

The Tsarphin would drop cod, bones, and Tsarphin teeth. Those teeth can then be used repairing a trident like phantom membrane repairs and elytra or adding to the end of tridents to up the attack power of the trident.

The Tsarphin can be found in Warm Ocean Biomes and its nests. 

The Tsarphin overall would be an awesome edition to Minecraft because of its new Curse, it's a shark-like mob people have been wanting forever, it has a new area in the Ocean (its nest), it has a new item, and includes an upgrade to tridents.