So because I'm insane, I have started making a third Splatoon conlang.
The Reef language (Dazat'e) is the fifth most widely-spoken language in the Mollusc Era. It's thought to have originated with crustaceans, and is now commonly spoken among non-cephalopod communities such as urchins, anemones, and some fish. Some traits of it:
Six vowels: a, e, i, o, u, and ə (the "uh" sound). Plus four diphthongs: ai, ei, oi, and ui
22 consonants: ch, ch' (ejective form), d, f, g, gh (voiced velar fricative), h, k, k', kh (voiceless velar fricative), l, m* n, r, s, sh, t, t', th, y, z, and ' (glottal stop)
The letter that's written down as "m" is extremely variable in pronunciation across species dialects: it could be pronounced as m, b, p, or (in crustacean dialects, since they do not have lips and therefore fully labial sounds are impossible) v
r, l, and n can also act as vowels, e.g. chrha "shoe"
Subject-verb-object word order
Verbs build off a root-pattern system similar to that of Arabic. For example, the verb "to walk" has the root form es_t_. Different patterns of vowels added in those two blank spaces will mean different things. "I walk" is esetə. "He walked" is esoiten. "A walk" is esate. Like that.
Thus, Reef is a fusional language. This contrasts with the mostly analytic Inklish, largely agglutinative Octolingo, and polysynthetic Salmonic
Four grammatical genders along which nouns, pronouns, and adjectives are inflected: masculine, feminine, collective (for animate plurals), and inanimate.
I think that many of the gear vendors would speak this.