Black Ghost Knife: Poor Eyesight, or a Myth?

[knobhill]

BGK's - including my current one - that react to movements outside the tank, and follow me from one side of the room to the other, etc.

couldn't they be following you since they can feel you move from one side of the room to the other? I have wood floors and my BGK's come out to greet me before they can see me. They can feel my footsteps and know it's feeding time. It sounds like what you are describing is a conditioned response.

 

[Specialk314]

hard to say, the electroreception allows them to sense their surroundings in the dark and in turbid conditions. they can tell whether it is a non-living or a living item in their electric field by the way the bends around or passes though the object.

i have noticed my BGK look at a falling bloodworm and not go after it but then it appears that it senses it near it's tail and backs up to eat it... i'd have to say that evolution chose for electroreception over eyesight... poor eyesight

 

[peewee]

poor eyesight.

 

[kansei]

I say poor eyesight , but the "electro" sense is better than the eyesight of any other fish I've kept . The reason is simple why would a BGK require the the development of good eyesight when it needs vision in mostly dark and turbid waters . Natural selection would have ones with the better "sense" live long and thus reproduce more eregardless of their eyesight . Also I have seen pictures of blind cave tetras and loaches with similar looking eyes . Also as for them "seeing us when we walk near the tank - glass is not a shield for magnetism and they fish could detect signal size/strength and direction and through conditioning "reconize you"

 

[Toby_H]

My (adult) BGK is my only fish that I can easily and consistently catch by hand...

 

[sbuse]

blind as a bat...

 

[dannyboiiii]

bgks can see maybe not as good as other fish but there not blind , they r nocturnal and live in sandy turbulant creek beds in nature and there for have adapted to use there electroreception sonar w/e like a bat uses theres..
and that being such a good sense they dont depend on there eyes as much as a normal fish but more on there feelings...so evolution picks waht works....
my vote is poor, look at those beady little eyes...

 

[benzjamin13]

Not completely blind, but they do have poor vision, using EOD to make up for their eyesight. A good example would be that I don't think they would hide in a "ghost tube" if they can see it was clear, but using EOD tells them that they are safe. Seems that their eyes are only good for detecting light.

 

[Hoyo12]

Good discussion.
Still have 8 for Good though. ?

 

[fook]

couldn't they be following you since they can feel you move from one side of the room to the other? I have wood floors and my BGK's come out to greet me before they can see me. They can feel my footsteps and know it's feeding time. It sounds like what you are describing is a conditioned response.

My ck definitely reacts to whats going on upstairs. Once the kids go to bed and the house is quiet he will swim all over his tank whether the light is on or not. If he is out and there is a loud thump or whatever upstairs he will dart to his hiding spot. I assume the activity upstairs creates some very small vibrations in the water that he can detect. He also comes out more when I'm the only person down there. I don't know if he can "see" me or sense me or if its just a coincidence he seems to be able to tell when others are present.