Aquabasalisk

Petrifying Gaze. If a creature starts its turn within 30 feet of the basilisk and the two of them can see each other, the basilisk can force the creature to make a DC 9 wisdom saving throw if the basilisk isn't incapacitated. On a failed save, the creature is magically reduced to 5 hp and they loose their memory, loosing all proficiencies, spells, and features that are not race related. On a success, they take 1d12 psychic damage and loose 1d6 time their age divided by 6.

A creature that isn't surprised can avert its eyes to avoid the saving throw at the start of its turn. If it does so, it can't see the basilisk until the start of its next turn, when it can avert its eyes again.

If it looks at the basilisk in the meantime, it must immediately make the save. If the basilisk sees its reflection within 30 feet of it in bright light, it mistakes itself for a rival and targets itself with its gaze.

If the basilisk were to die then all memory related effects are undone.

Amphibious. The creature can breathe air and water.

Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) piercing damage plus 7 (2d6) bludgeoning damage.