What is the most intelligent fish in the ocean?

The most intelligent fish in the ocean is widely believed to be the dolphin, which is a mammal rather than a fish, but they are commonly found in the ocean. Dolphins are highly social and have demonstrated cognitive abilities, such as problem-solving, tool use, and self-recognition.

Other fish that are considered to be highly intelligent include the octopus, which is known for its problem-solving abilities and ability to use tools, and the cleaner wrasse, which has been observed working cooperatively with other fish to remove parasites from their bodies.

It's worth noting that the concept of intelligence can be difficult to define and measure in non-human animals, and there is ongoing research and debate about what exactly constitutes intelligence in fish and other marine creatures.