I think most people confuse "mental capabilities" with "intelligence"

Altho humans have much stronger abstraction and conceptualization capacities than fishes, they often use these capacities to increase their own stupidity

For an extreme example, a girl once told me that she will "get back what 'they' stole her" and be the millionaire she was mean to be, I guess she was talking about the secret elite rich reptilians or something alike, then she proceeded to tell me she's Jesus, because "I am" is pronounced "je suis" in French and it sounds like Jesus.

See, her mind created a lot of things a fish could never dream of. Still, her mental capacities made her dumber than a fish.

Another less extrem example: fad diets, for example there was a time some people would say that digesting kiwis uses more calories than the kiwi will give you, thus, eating more kiwis will make you lose weight.
Even if fishes could talk, I don't think any of them would tell me something alike.

Others examples: astrology, homeopathy, investing in NFTs, Ponzis, giving your bitcoins to Elon musk so he send you back the double, angrily screaming at your kids to be happy, fruit-only diet (yes...), trying to make money by regularly robbing it, and plenty others things that would be more controversial because a lot of you here are at a lower intelligence level than fishes.

Basically, most of the times, walls, fishes, clouds and squirrels are less dumb than humanoids