Kava Kava?

[kasa_balavu]

E.g. the word "fish"
-"ika" (Samoan/Tongan)

It's ika in iTaukei (ethnic Fijian) as well.

 

[verticity]

In some languages (e.g. Indonesian) one can repeat words to indicate their abundance. E.g. "barang" - a thing, "barang barang" lots of things. As you can see "lots of" isn't necessarily shorter than simply repeating the word barang.

I think Indonesian/Malay is actually related to the Polynesian languages. I used to speak Indonesian (haven't spoken it for close to 10 years so I cannot remember almost anything) and often notice similarities between some of the most popular Polynesian words and their Indonesian or Malay equivalents. E.g. the word "fish"
-"ika" (Samoan/Tongan)
-"ikan" (Indonesia)

Yes, Indonesian and Oceanic languages (and also Malagasy in Madagascar) are all in the Malayo-Polynesian subgroup of the Austronesian language family:
https://en.wikipedia.org/wiki/Malayo-Polynesian_languages

 

[verticity]

There are lots of similar words:
https://en.wiktionary.org/wiki/Appendix:Cognate_sets_for_Austronesian_languages