Can fish smell?

Question

Do they have a sense of smell to detect scents in the water?

Answer 1

Very nice answer from Freight Train, what a shame it was stolen from this site
http://amos.indiana.edu/library/scripts/fishnares.html


Yes, fish can smell. All jawed vertebrates (including ourselves!) have three pairs of sensory capsules in the head: from back to front, the otic capsules (ears - balance and hearing), the optic capsules (eyes - vision) and the olfactory capsules (smell). The latter open to the outside via the nostrils, and unlike our own nostrils, fishes' nostrils are not connected to the roof of the mouth; they form closed sacks lined with specialized sensory cells.

In a cartilaginous fish such as a shark, there's a single nostril at each side of the snout, opening to the water and leading to a chamber lined with the chemosensory epithelium that "smells" specific molecules dissolved in water. Each nostril has a small flap of soft tissue that acts like a partial separation, so that water with chemical information flows in at one half of the nostril, and out from the other half. That arrangement enhances water flow through the olfactory capsule.
This is a photograph of a shark's head, you can see the nostril and the fleshy flap I was talking about:
http://www.sharkattacks.com/Image15.gif

In bony fishes, there are two nostrils at each side of the head. And as you might have guessed, they're connected by a duct lined with olfactory epithelium. Water goes in one nostril and out the other nostril at each side of the snout (right and left pairs are separated).
See this picture, it's a moray eel:
http://www.flmnh.ufl.edu/fish/Gallery/Descript/GreenMoray/moray--NOAA2.JPG
The incurrent (=inflow) nostrils are tubular, and you can see the excurrent (=outflow) nostrils a little to the rear and more to the middle.


Smell is very important for fishes, and the water is full of chemical cues that they can capture and interpret to detect food, enemies, potential mates, etc.

I hope this helps :-)

Answer 2

Can fish smell? That's the question for this Moment of Science.

Dave: I've noticed that fish have little holes that look like nostrils. Does that mean they can smell?

Don: Smell, or olfaction, as scientists call it, is an important sense for many fish, Yaël. Those little holes that look like nostrils are called nares. Nares don't lead to the throat the way nostrils do in mammals, but open up into a chamber lined with sensory pads. Not all fish move water in and out through these nares in quite the same ways, but key to a strong sense of smell for fish is the ability to move water rapidly over these sensory pads. Some fish can pick up chemical signals when immobile by pumping water through their olfactory system via tiny hairs called cilia. Other fish can pump water by a muscular movement. Some fish, such as smaller species of mackerel, have an olfactory system that requires them to swim in order to get water moving through their nares. When the sensory pads pick up chemical signals, they transmit them to the fish's forebrain, which interprets the signal and incites the fish to respond appropriately.

Dave: You mean like if the chemicals signal food, the fish will pursue the food. Or if the chemicals signal danger, it'll flee.

D: You got it. But fish use chemical cues in all sorts of ways. For instance, a large group of fishes, including minnows, release a chemical when they're wounded that incites other fish to flee. And then there are salmon, which are known for a superb sense of smell that enables them to sense the stream where they were born, so that they may return to it to spawn.

Answer 3

Yes many of them have an acute sense of smell. Take Sharks for example they use their sense of smell to zero in on wounded fish or seals.

Answer 4

Fish have chemoreceptors that detect dissolved substances in the water. They basically "smell" that way.

Answer 5

yes fish smell they have small nostrils

Answer 6

Yes, it's true fish do smell. And thats why we hook our minnows through the nose, so they dont smell so much!

Answer 7

they use sonar