"Rōvra issi?"

[NLiddy10]

How would you ask "Is it big?"

[BrunoSenra]

"Rōvor issa?" would be singular, but I'm confused about the use of adjectives without any nouns. Why would we assume "they" to be aquatic? Would this only happen in a specific context when it's implicit? Hmmm

[FelipeKail.an]

Rōvra issa?