"[F]ish had their lips injected with
chemicals that would produce a painful sensation....Before they received the injections, the fish showed normal behaviors. After,
however, the fish began to rub their lips against the gravel and walls of their
tanks....It was also found that their breathing rate nearly
doubled. The researchers then treated the fish with morphine....The fish began to rub their lips
much less, and their breathing rate lowered significantly as well....The same research team did further
studies on fish pain, and also found that when experiencing painful stimuli,
the neurons of both humans and fish brains fire in the same way."
"[In another study], one set of fish were given morphine, and
another set was given saline. Then, they were exposed to hot water. All of the fish
tried to escape the heat, but the ones that received the pain-relieving
morphine had slower responses. After the initial exposure, the fish would avoid
the heat source. 'The experiment shows that fish do not only respond to painful
stimuli with reflexes, but change their behavior also after the event. Together
with what we know from experiments carried out by other groups, this indicates
that the fish consciously perceive the test situation as painful and switch to
behaviors indicative of having been through an aversive experience.'"
Read full article HERE.
