Is there a species of fish that is generally regarded to be the most intelligent?

Title pretty much says it all.

What about salt vs. fresh water.

Title barely scratches the surface! Do you want to include all sea creatures, or are we excluding mammals? How about cephalopods like the octopus, which can open jars from the inside after watching people do it a few times? With “fish” I guess we can assume you mean just the scaly vertebrates.

I’ve heard fishermen talk about the cunning of particular types of trout and bass and catfish, but then fishermen talking about fish is about as reliable as a politician talking about what they’ll do if elected. Goldfish can be trained to swim through hoops, but that’s not much better than stimulus-response.

Groupers have been observed persuading moray eels to hunt with them, using a dance to communicate the location of the prey and offer to cooperate on the kill. That seems pretty smart to me, but I don’t know where it would fall on the intelligence scale.

The last time I checked mammals are not fish but maybe I’m wrong. Your assumption is the correct one.

I’ve seen film of one opening a jar that had food in it, but not opening one from the inside. Is that to escape from a jar?

I had heard about this apocryphally, and the motivation given was to escape, but I probably should have found a cite before stating it. I can’t find one, so I’ll reduce my claim to “they can open jars from the outside”.

Cuttlefish are pretty damn smart, too. If you ever see the Nova episode on them, watch it.

One possible datapoint - when I walk past my aquaria, my angelfish come to the front and act excited, as tho they expect me to feed them. Other species - cories, tetras, rainbows, plecos, do not. Of course, this may mean the angels have better eyesight than the others.

I have heard many folk who keep oscars and piranha comment on their fish exhibiting personality and apparently learning - such as being able to be hand-fed, suggestive of intelligence.

It turns out fish are more intelligent that we usually think. Here is a link to an interview on NPR with Dr. Jens Krause, University of Leeds biology professor, who authored an article recently on fish intelligence. Also, for what it is worth, Here is a link to a web site that is devoted to fish intelligence.

Well, they do travel in schools.

(I’ve been waiting since second grade to use that one.)

My danios learned after about two days that if they crowd next to my beta when I open the lid, they can steal his food, which is better than their smeppy spirulinia.
I swear, I have the wussiest beta ever spawned.

Darn, I was thinking about The War of The Worlds radio broadcast, and the Martians unscrewing the hatch to their spaceship. :slight_smile:

My housemate’s goldfish used to do that, too. Plus the whole “five minute memory” thing about them is untrue anyway, but I think they’re reasonably smart.

Cuttlefish are not fish, they’re invertebrate cephalopods like squid and octopus; this is a completley different phylum from fish.

Depending on how you define “fish”, the layman concpetion of which is not encompassed by a single clade, you’ll have a wide range of different behavior and environments. The intellectual capability of non-mammalian sea vertebrates is pretty limited, though; fish tend to be very highly specialized in what they eat and how they behave, so the sort of generalizing intelligence so useful in terrestrial environs doesn’t seem to have developed among native marine vertebrates, though many members of class Cephalopoda have reguarly demonstrated high levels of learning, memory retention, and adaptation. I did once own an oscar, and he was certainly amenable to a limited amount of conditioned response, including recognizing my finger (probably by smell) and associating it with imminent arrival of live guppies, but I wouldn’t go so far as to consider this cognitive intelligence in general form.