Christians, as well as the non-religious, have either responded to or made spin-offs of the Darwin fish. A design supporting a version of that rejects biological evolution was made with a larger Jesus fish eating the Darwin fish. Sometimes, the larger fish contains letters that spell the word "Truth". A further development shows two fish, one with legs and labeled "I evolved", the other legless and labeled "You didn't".
Another variant has a Darwin fish with an open mouth, carrying away a smaller, dead Jesus fish by its tail. Other variants depict an "Evolution" or "Darwin" fish swallowing an "ΙΧΘΥΣ", "Jesus" or "Truth" fish; another version has a "Science" fish swallowing a "Myth" fish. Supporters of the theological concept of , also known as theistic evolution, have responded with a of the Jesus fish in which the word "Jesus" is written inside an ichthus fish with stylized feet.
Rhetorical scholar Thomas Lessl has conducted a questionnaire survey of users of the Darwin fish emblem. Based on their responses, he interprets the symbol as scientific "", a parody that is one part mockery and one part imitation.
Thomas Lessl suggests that the "various ideas that users plainly compress into this emblem are suggestive of ", and adds that the Darwin fish is an advertisement for , an idea, which according to Lessl, is "now thoroughly discredited by historians". , in criticized the Darwin fish, stating that: