It depends
Imitation crab is typically bound with wheat starch. On a US label the wheat would be declared, so check the allergen statement.
White fish — usually Alaska pollock — washed, minced to a paste, and set with starch and egg white into a block that can be cut, coloured and sold as something else. Imitation crab, krab, seafood sticks and a good deal of what goes into a California roll are all surimi.
Because the binder is frequently wheat starch, and because nothing about the product suggests a grain is involved. It is sold as fish, sits with the fish, and is eaten by people who are being careful about bread.
In a supermarket, read the allergen line and the answer is there. Eating out, treat anything described as crab stick, seafood stick or imitation crab as wheat until somebody tells you otherwise — and be aware that a California roll is one of the most common ways somebody eating "just sushi" gets glutened, alongside the soy sauce.
Because the answer depends on the rest of the label, scanning the actual product is the only way to resolve it — CiCi checks for a gluten-free claim, the allergen statement, and which agency regulates that label, then tells you which way it lands.
Every one of these is the same ingredient. The number of names is a large part of why gluten slips past people who read every label.
Point CiCi at the barcode on the product you're holding and get this same reasoning in about two seconds, plus the carbs and the full nutrition panel. 360,000+ packaged foods are already read and waiting.
This answer comes from CiCi's ingredient lexicon — the same rules the scanner uses, not a separate article. Where reputable sources disagree, CiCi takes the conservative position and says so.