Throughout The Shape of Water, we see Giles working on a painting for a Jell-O type company. At first he paints red gelatin and is asked to redo his painting, making the gelatin green and the family look happier. Giles thought that this looked fake and didn't like the idea.
Then towards the end of the film, the last time that we see Strickland's family his wife says something like "Come sit down, I just made some Jell-O!" and I noticed that her Jell-O was green and looked exactly like the Jell-O in Giles' second painting. Then I realized that Strickland and his entire family were dressed like the fake happy family in Giles' painting. Strickland became more and more unraveled throughout the film and I feel like this was a small detail to show just how far he had sunken by then end.
Loved the movie!