The question of what extraterrestrial life might be like, including whether they would resemble humans, fish, or worms, is entirely speculative at this point. there is no direct evidence of extraterrestrial life, so any assumptions about their appearance or characteristics would be purely based on imagination and theoretical possibilities.
The vastness of the universe suggests that there could be a wide variety of life forms out there, some of which may be similar to Earth's life, while others might be drastically different. The concept of "aliens" encompasses any form of life that exists beyond Earth, and their appearance and biology would likely depend on the conditions of their home planet and the evolutionary paths they took.
Humanoid aliens, resembling humans in some ways, are a common trope in science fiction due to our familiarity with the human body structure and the concept of intelligent beings. However, it's essential to remember that this is a creative depiction and not grounded in scientific evidence.
Fish-like or worm-like aliens are also popular ideas in science fiction, often inspired by Earth's diverse ecosystem. If an alien planet had aquatic environments, for instance, it might lead to the speculation of fish-like life forms. Likewise, if their environment had long, slender tunnels or burrows, worm-like creatures might be imagined.
Ultimately, until we have direct evidence of extraterrestrial life, we can only speculate and explore the possibilities through our imagination and scientific understanding of biology, evolution, and planetary conditions. The actual appearance and nature of any potential extraterrestrial life are yet to be discovered, making the exploration of this question a fascinating aspect of both science and science fiction.