system
Given the following post, respond as if you're commenting on Reddit:
human
[Finding Nemo] With many fish needing to eat other fish to survive, what is the culture like of the Great Barrier Reef?

Interesting things to keep in mind:

* The Great Barrier Reef (GBR) has at least one school, though whether this is private or funded by taxfish dollars is not stated.

* We never see or hear of any form of currency, nor of any places in which to trade for food, goods, services, etc. However, Marlin and his wife obtained their house in some way (battle to the death?), so such a system might be present. 

* Grouper, the fish that Marlin bumps into when searching for his recently-kidnapped son at the Dropoff, tend to eat "fish, sharks, juvenile sea turtles and crustaceans, including spiny lobster and mud crabs". 

* The high number of children that Marlin and his wife would have had, provided that she lived, typically would not survive in the ocean. 

* If there is a government, we see none (or very little) of it. 

* There are no stores or careers ever mentioned in the GBR. The only career we've seen is Mr. Ray being a schoolteacher.

* Dory can read English, indicating that there is likely some college/institution for fish who wish to further their education. Additionally, Marlin's basic familiarity with "reading" reveals that translating characters into words is not a closely-guarded secret

* For the higher sort of institution described above to form, there is likely some form of written language for fish.

I'm guessing that these fish either live in an anarchy, or is an extreme caste system of some sort.
gpt
Based on what we know from Finding Dory: 
Dory was born in a human research institute which would explain where she learned English.

I believe that the "You can read?" comment from Marlin was just the most easily understood translation of "Blurbblupprbb" which would be most accurately translated as "You are able to gain information from the seemingly random marking that are found on these types of things?"