The Water Dragon will behave somewhat identical to the Enderdragon, but it has different attacks of a different type. It has two thousand hitpoints (1000 hearts, if you would be playing vanilla o.o) and does 21-61 ice damage. It will only take damage from Firebolt wands, Lightning Bolt wands, the Mage's Fireball and Charged Bolt spells, items that have prefixes/suffixes that increase fire or lightning damage (but will only do the fire/lightning damage) and fire-based scrolls. This dragon can be found in the Mystery Dimension.
The Water Dragon has several attacks other than it basically just "touching" you.
This attack will cause 5 "waterballoon-like" balls to appear and start bouncing around, creating a water block everywhere it bounces. These will do the player 12-21 Ice Damage if the balls hit him.
This "attack" (its more of a defense) will make the Water Dragon regain 25% of its health. This will rarely occur and only if under 45% health, making it an annoyance to fight.
The Water Dragon's egg can hatch just like any other dragons' egg, but instead of Obsidian or Glowstone Dust around it, Ice Blocks need to be used. After 7 in-game days, the egg will hatch and the ice on the outside will have darker blue-ish veins in them. These blocks can be broken without any tools, and the first player to break one of the blocks will become the dragon's owner. A "Wet Dragon Saddle" needs to be used to mount it.
You must feed it with one raw fish every in-game day, or it will become Feral, and hostile, and you will get an egg from it, as it is a Purebred Dragon. The way to cure this dragon from being feral is to to pour a bucket of water over it's head this can be quite hard to do in survival mode.
When being riden click F to use its primary attack Bouncy Balls and click G to do the secondary attack Frozen Fury, Frozen Dury also gives the player full health.