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Zebrafish

Danio rerio

A small fish widely used in neuroscience. Its neurons haven't been fully counted. The adult brain has about 10 million cells.

Neurons

No published count

Evidence

• Fish have nociceptors and change their behaviour in ways linked to pain. This was shown in trout, and it's used here as the reference for fish, not as a result for zebrafish.
  Sneddon LU, Braithwaite VA, Gentle MJ (2003) Do fishes have nociceptors? Evidence for the evolution of a vertebrate sensory system. Proc R Soc Lond B 270(1520):1115-1121. doi:10.1098/rspb.2003.2349.

The New York Declaration on Animal Consciousness (2024) finds at least a realistic possibility of conscious experience in all vertebrates and in many invertebrates, including cephalopods, decapod crustaceans and insects.

Assess it against the published criteria