Literally just some raw salmon, they eat it like a delicacy.
Obviously speaking from their own biology, Ilthenese are water lovers, often taking up most of their time in or around water as a form of entertainment. Swimming, Fishing, and other water sports are popular among the poorer classes, while Nobles enjoy the relaxing warmth of a fire-warmed pool, or small bath. As a result of this, most Ilthenese are fairly clean in terms of hygiene, save for the few who don't necessarily live near water. Ilthense are very hygiene-centric, often shying away from tasks that may seem unclean to them, and even if they are meant to do so, it is expected that they use some sort of protection, be it a cloth or their own mucus.
In addition to water sports, Ilthenese are fairly well versed in writing and music, their own music having tribal yet orchestral tones to it. Often times, music is performed by street performers, but can be viewed in large theaters at times, which is often announced via paper or a designated announcer. A cultural instrument of the Ilthenese is the Dumilin, a long, bumpy instrument which is played by wetting the fingers and rubbing strips of smooth material, which creates a soft, flute-like noise.
When not in public spaces, Ilthenese prefer to be isolated and alone, believing that "private spaces are for private people". It is considered extremely rude to enter a private space without prior invitation, Ilthenese often react poorly when not given some amount of privacy, though often times, this reaction is less poor if family, or significant others are within the area.
Ilthenese often duel for fun, often with magic rather than swords.
Overall, Ilthenese are water loving, private individuals with a taste for music, and holding their breath for contests.
Ilthenese, being entirely carnivorous, have developed a meat-based food economy. Said economy is mostly fueled by seafood, in which Ilthenese often dive down into bodies of water to catch food as both a past time and a way to pay for basic needs. Often times, Ilthenese will simply eat what they catch raw, but may occasionally cook it if they wish. Food is well made with taste in mind, often being rather salty, and blended in with dairy products, such as eggs, roe, or cheeses. Most Ilthenese prefer mild cheeses, preferring to simply fill their mouth rather than experience anything sharp.
Being that Ilthenese are rather bad at chewing tougher meats, such as beef or chicken, those kinds of meats are often mashed into a more easily chewable form, like a pate or paste. As a result, cattle farming is a rather niche and rare, but still fairly rewarding as a career.
As being a carnivorous species, they have little ability to digest plant matter, often expelling it via waste or simply vomiting it out. As such, it's a popular punishment in Ilthenia to force feed convicts plants for the sake of making them sick infront of people. Of course, this is for minor crimes, like theft and vandalism.
Ilthenese have a loose concept of clothing, it being used as simple shelter from the elements, rather than any sort of coverage against embarassment, nudity is commonplace among Ilthenia, and often times, only those away from their watery cities wear clothing, merely to protect them from the elements while they do their work. Most Ilthenese clothing is designed in part for this, often being thick, baggy, and lined with tear-resistant materials, like rubber or leather. Despite having tails, Ilthenese tend to tuck them into their clothes, along with their mantles.
Ilthenese are suckers for jewelry, often wearing it in tandem to their clothing (or lack of) for the sake of vanity. Necklaces and piercings are most popular due to their convenience and ease of use. Gems and polished metals are very populer, which the most used gem in their jewlery being Amber, due to its contrasting color with the Ilthenese's own colorful bodies.
Magic is something well known to Ilthenese, a widely researched subject, magic is used in fairly small amounts by almost all Ilthenese. Their grasp on magic is weak, much less destructive or powerful as other races, but they have a grip on it nonetheless. Thaumatology is a basic subject in schools, with it being distributed among 3 classifications, Restorato, Desrutu, and Alatreon. The three Ilthenese classifications of magic is complicated, but it simply boils down to the characteristics of a magical spell or entity.
Nearly all Ilthenese have some ability to use magic, either alchemy or elemental magics of some sort. Although it is a very simple understanding of magics, with most being unable to afford the more complicated proceadures of magic. Nobles and the like, able to afford more and better lessons, often have a much more powerful grip on both what magic is, and how to use it effectively, making them exceptional..atleast compared to other Ilthenese.
Magic is considered a useful tool in Ilthenese culture, something that can be used to aid work, or help prepare dinner. Most Magic used by Ilthenians is contact based, meaning it has little to no effective range, and must be applied by touch upon whatever the Ilthenese want to be "magified".
While Ilthenia has no state religion to date, one spiritual theory is dominant among philosophers and townsfolk alike. The concept of what is known as "the Dark Tide", it is the Ilthenese concept of inevitability. Just as how the tide of an ocean pulls grains of sand up and throughout the beach, so to does this dark tide pull all creatures to their inevitable fate among the waves. Ilthenese often mention the Dark Tide in euologies, or when something seems to always happen despite attempts to prevent it. It is in the same manner that a person cannot fight a strong current, they will be pulled around, spun about, and in some cases, dragged down to their doom.
The Ilthenese believe that all creatures are a part of this concept, that each person plays a part in the fates of one another. Avoiding it is useless, as most will find that they meet their end to the Tides on their journey to avoid it.
The Ilthenese, however, have little belief in the supernatural, recognizing magic, souls, and other seemingly paranormal things as a simple part of the world, a thing they have yet to understand fully, and something worth knowing about to a great degree. Ilthenese rarely believe in religion, some might even study it. For this reason, most of all forms of spirituality are accepted within their culture, so long as it does not involve bloodshed of most kinds.
In this same reasoning, spiritual healing is an unpopular method of healing within Ilthenia, often being regarded as a mere placebo to actual healing spells, or medicine.