contact the developer directly.
Here is the developer of Aquatic screensaver https://serenescreen.com/v2/
Roku likely had an agreement with this developer to customize the screensaver, compiled for Roku and published by Roku as an official Roku screensaver. That is why it lists Roku as the developer. Roku is not the actual developer and likely would not be able to make the requested changes. This screensaver uses the Roku NDK (native developer kit) that most developers here would not have access to.
Here are post addressing this. A quick search to the forums would give you.
https://community.roku.com/t5/Roku-Developer-Program/How-is-Aquatic-Life-implemented/td-p/502845
https://community.roku.com/t5/Roku-Developer-Program/aquatic-Life-Suggestion-Little-Crab/td-p/542827