Mermaids (The Sims)

Mermaids are a life state that were introduced in The Sims 3: Island Paradise and in the Sims 4: Island Living.

Becoming a Mermaid
A Sim can become a mermaid via eating the Mermadic Kelp, which can be obtained by talking with a mermaid underwater, or by purchasing it from lifetime reward for 25,000 lifetime happiness points. The Sim must be human in order to transform into the Mermaid life state. In the Sims 4, a Sim can create a mermaid in Create A Sim. A human Sim can become a mermaid by eating Mermadic Kelp which they can find in caves, while cleaning up the beach or by asking a dolphin. A mermaid can become human by eating two pieces of Mermadic Kelp in a row.

In both games, a mermaid is a genetic life state. There is a 50% chance a child will be a mermaid for each mermaid parent. If both parents are mermaids the child will be 100% mermaid

Sims 3
The mermaids can be encountered in sea when diving or riding with a boat. They can also assume human form and walk on land.

Needs
Mermaids needs vary from regular Sims in two ways: Even if a Mermaid is well hydrated, they need to swim in the ocean at least once every 48 hours, otherwise they'll get a "Salt Water Deficiency" moodlet. Within a day this will turn into "Adapting to Land" and when this moodlet expires, the mermaid will turn into a normal Sim. Purchasing the "Permanent Mermaid" lifetime reward will prevent the Mermaid from losing their occult status.
 * Hydration - In place of Hygiene, there is a "Hydration" need, similar to Water for a PlantSim. This can be satisfied by swimming in the ocean or a pool, using the shower or bathtub, or relaxing in a hot tub. If The Sims 3: Seasons is installed, they can also hydrate by standing in the rain. Dehydration will cause the Sim to dry out, giving them a negative moodlet. Eventually they will pass out, and if another Sim does not splash water on them, they will die.
 * Hunger - Mermaids don't get much energy from normal meals. Instead, they require fish and kelp. Fish can be caught from fishing or while scuba diving, and can be eaten raw. If a Mermaid has the Vegetarian trait, eating fish will make them nauseous. Kelp can be harvested from diving areas or purchased from the grocery. If a Mermaid's hunger need is very low, eating two pieces of kelp is enough to fully replenish it.

If a mermaid is near a fireplace or in the sun for a while they will get a moodlet causing their Hydration need to drop faster than usual until they move away and the moodlet expires. The moodlet lasts three hours.

Appearance
Mermaids have dolphin/fish-like tails covered in scales. Mermen have straight, sharp fins and go shirtless, mermaids have curved fins and wear seashell tops. On land, a mermaid's tail will turn into human legs covered in colorful fish scales. Mermaids gain these scales as toddlers but will only gain a tail once they become teenagers.

The color of a mermaid's scales and top can be changed using the "Change Scale Color" interaction via a mirror.

Abilities
Mermaids have various water-related special abilities. They can breathe and stay underwater indefinitely, and will not get the "Depressurising" moodlet when returning to the surface. This makes the Steel Lungs lifetime reward useless for them. Mermaids swim faster than normal Sims on the surface and underwater. Once a mermaid becomes a teenager they will automatically maximize their Scuba Diving skill. Mermaids do not need umbrellas when it rains, and they will get a positive moodlet when they get soaked.

Like normal Sims, mermaids who possess a conch shell are able to summon another mermaid they have met. Mermaids with the Mean Spirited or Evil trait are able to summon sharks to attack other divers. Mermaids are safe in their aquatic environment and will not be attacked by sharks, however they can be attacked by the cave monster. If mermaids are on a boat, they will not be attacked by the Kraken.

Sims 4
Mermaids return in the Sims 4: Island Living.

Needs
A Mermaid's needs are different to a Sim in one way: Once a Mermaid's hydration need is empty, they will not become human or die; instead, they will remain extremely uncomfortable until they can hydrate their skin.
 * Hydration - In place of Hygiene, Mermaids have Hydration. Mermaids need to regularly hydrate their skin to stay happy, they can satisfy this need by drinking water, taking a bath, and going into the pool or ocean. Hydration is also needed to use their mermadic powers. Being out in the Sun drains their hydration need faster than at night
 * Hunger: Unlike in The Sims 3, a mermaid does not need to eat just kelp and fish. In fact if a mermaid Sim eats something made of seafood, they will get a 1+ uncomfortable moodlet stating Stomach Squall (From eating fish) Devouring the fishy friend has left a foul feeling within. This moodlet will last 4 hours in total. Other meats are okay unless the mermaid is vegetarian.

Appearance
There are four different tails for mermaids, each with a wide array of colors and patterns but also an attribute that sets each tail apart; like sparkles, bioluminescent spots or swirls. There are two types of tail fins. Mermaids can use human swimwear or choose from four different mermaid tops. Mermen can also use a top of kelp and netting. Mermaids can also have different skin tones, including purple, blue or green, different eyes with unique irises and scales for their faces and shark teeth.

Powers
Mermaids have an array of powers that are based around water. Depending on if they have a good or evil trait; Mermaids have different powers, however, if Mermaids have neither trait, they have all the powers. If Seasons is installed, these powers are self-interactions:
 * Siren's Lullaby...
 * Aegean's Question (-30 Hydration): This lullaby makes the target Sim tense.
 * Charmer's Lullaby (-30 Hydration): This lullaby makes the target Sim flirty.
 * Inspiring Berceuse (-30 Hydration): This lullaby makes the target Sim inspired.
 * Night's Requiem (-30 Hydration): This lullaby makes the target Sim sad.
 * Mermaid's Kiss (-30 Hydration): A Mermaid's Kiss grants whoever is kissed the "Aquatic Breath" moodlet, which temporarily gives Sims the ability to dive underwater for longer periods of time. This ability can be used in and out of water, but is more powerful in water.
 * Aquatic Lure (-30 Hydration): Calls fishes to nearest water for fishing, it also calls more rare fish.
 * Call for Dolphins (-30 Hydration): Calls for Dolphins and Dolphins the Mermaid is friends with.
 * Siren's Call (-100 Hydration): Mermaids can lure a Sim to them in the ocean and once near, the Mermaid will dive underwater and drag the Sim down into the water. If repeated enough times can cause the Sim to drown. (Unavailable to Mermaids with Good trait). Mermaids will regain all their needs by performing this action.
 * Summon Ocean Threat (-30 Hydration): Mermaids sing a haunting song that summons a black mass underneath their target that swallows the Sim. If repeated enough it can cause the Sim to drown. (Unavailable to Mermaids with Good trait)
 * Call Clear Skies (-75 Hydration): Clears skies of any rain or thunder. (Unavailable to Mermaids with Evil trait)
 * Call Rainstorm (-75 Hydration): Summons a rainstorm.
 * Call Thunderstorm (-75 Hydration): Summons a thunderstorm. (Unavailable to Mermaids with Good trait)

Abilities
Mermaids also have a few abilities which don't require hydration:
 * Mermaids can utilize conch shells that can be found at the beach to access other abilities; Mermaids can blow through the conch shell which will attract nearby Mermaids to the Sim's location.
 * Mermaids are naturally great swimmers, they can swim at fast speeds, as fast as an Aqua-Zip.
 * Mermaids can talk to fish, which fills their social need.
 * Mermaids can sleep in the water.
 * Mermaids can sunbathe in water, however occult skin tones will not tan.
 * Mermaids don't need to be level 3 of Fitness skill or purchase scuba diving gear to free dive.
 * Mermaids can swim within their third trimester of pregnancy, unlike normal Sims.

Links

 * https://sims.fandom.com/wiki/Mermaid