Amphibious. The dragon can breathe air and water.
Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 7 1d10+2 piercing damage plus 3 1d6 poison damage.
Poison Breath (Recharge 5-6). The dragon exhales poisonous gas in a 15-foot cone. Each creature in that area must make a DC 11 Constitution saving throw, taking 21 6d6 poison damage on a failed save, or half as much damage on a successful one.