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The Loach Forum Archives (2)
Re: How do fish smell?
Posted By: Iris <Iris6@aol.com> In Response To: How do fish smell? (Dr. Momfish)
Date: Tuesday, 25 January 2000, at 10:44 p.m.
"I'm not going to stoop to the obvious comments here, although it's tempting...:)"
That's because you're a woman of taste and distinction. Martin, now, would not pass up the chance (hee hee Martin, running for cover...)
"They have nasal openings. If you look at their 'faces' you will see at least two nostril holes. They, especially loaches, have a superb sense of smell because oftentimes they live in murky waters especially during rainy season."
I've noticed those openings on loaches and other carp-like fish. I wondered what they were used for.
"The only thing I wonder about, is after dinner is eaten, does the tank water have the smell equivalent to the fish that a McDonald's restaurant does to us? Blechhhh."
Good carbon probably takes care of that. I assume from what I've watched of tetra schooling (chemical signals) that dirtier water *does* affect the fish ability to detect things - so it probably is "bleccchhh" to them, too, if the filtration is not working properly. (No, folks, I'm not abusing fish with dirty water in the name of science. I posted this little tidbit elsewhere.)
"Clown loaches also have extremely good eyesight. I don't know if it's 20/20 vision, but they are very aware of any movement outside or inside the tank and they do a wonderful job of slurping up bloodworms that are moving in the current. Red spaghetti....mmmmmm. Ever tried counting how many bloodworms a single loach can suck in during one meal? I quit after 30. They are porkers."
Oh, yes, I've noticed how many they can eat, and how quickly they can eat them. The Chinese/Thai name for loach is "pig" - suitable, isn't it? My modestas just sort of pass by and suddenly there are no worms in the tank. They inhale them so quickly I don't even see it happen.
As for loach vision, I wonder if it is like the vision of other carp-like fish, notably goldfish. Goldfish have infrared vision! Yes, they can see you in the dark. Someone did experiments that showed up on one of those Public Television science shows a few years ago. Now, since loaches are largely nocturnal, I wonder if they also have infrared vision - it would be useful.
"Corydoras seem to hunt their food by smell and feel. The way they bop around the gravel, millimeters away from a brine shrimp, you'd swear they were blind. My one eyed cory has grown to be much bigger than her two eyed conspecifics. Clearly vision doesn't seem to be so important."
Corydoras can actually see quite well - they can see you for a considerable distance away from the tank - but for some weird reason, they don't use vision for food that I've noticed. Experiment by placing yourself in front of a cory and rolling your eyes at the corydoras. Every cory I've done this to will roll its eyes in response! This is more than just a random eye-rolling on their part - it seems to consistently be a response to my eye-rolling, meaning they have to be able to see it.
Their barbels are incredibly sensitive and they seem to rely on them for food detection. Healthy corys have long barbels, which can reach into the gravel to detect morsels.
Well, that was fun. I love this kind of thing. Thanks for the answer! I really didn't think those nostrils were really nostrils.
Iris
