Help settle a debate.

[Disco Davros]

Hi folks, let me just start by apologising if this is in the wrong forum, anyway, can anyone help me and a friend settle an argument?

A work college of mine claimed today that if you pull a fish backwards through water it would result in drowning the fish. inevitability it led to a prolonged debate, with me arguing that it was a load of nonesense. I personally haven't ever heard of anything like that, but after having a couple hours worth of his Pseudoscience thrown at me I begun to question myself.

Is there anyone out there who has a basic knowledge of marine biology and can either confirm or debunk this statement?

Cheers folks, i know how ludicrous this sounds.

 

[The Great Wallsendo]

Good question - right forum - don't know

Pseudoscience (great word) to me says that as long as water is passing over the gills - in whatever direction - then the fish will be fine...I think

 

[mark1964]

i dont know about marine.but i have a large koi pond and quite deep. i do know if you drag a koi backwards it drowns. something to do with the gill plates and the pressure on the swim bladder i think.

 

[jonny_s]

Its all about flow of water over the gill filaments. If a fish is dragged backwards and its gill plates are open and its mouth is open then water will flow through and it will get its oxygen. If mouth is closed or gill plates are closed it will eventually suffocate.

The structure / shape of the filaments suit water to flow in the correct direction. water flowing in the wrong direction may result in less absorbtion and possible damage.

But then again I might be wrong

 

[Mad as a fish]

My dad told me that when i was a young lad, I am nearly sixty now.
He said a fish gets its oxygen from the water through its gills so i reckon if the water is going through its gills the wrong way it would suffocate.

 

[phill_itofish]

Foul hooked a coaley last week right in the tail dragged it in backwards unhooked it and it swam away strong

 

[Mad as a fish]

Foul hooked a coaley last week right in the tail dragged it in backwards unhooked it and it swam away strong

Maybe you did not drag it far enough

 

[super-MAGuire]

Yeah, i have a degree in marine biology, it may not directly kill the fish, but it isnt optimum. As the blood throw through the gills means their is a high difference in the oxygen/carbon dioxide between the water and the bloodstream of the fish. As water goes forward O2 is take away, so lower concentrations, but further back their is higher CO2 levels so mainiting a strong gradient for diffusion, so the fish swims forward it adborbs as much of the O2 in the water as possible and diffused as much co2 out. Also nano structures on the gills which increase the surface area are disrupted and so slows the diffusion or makes it less efficient.

Thats the basics, obv its different for different spp and so on, esspecially eels and some can obtain oxygen through their swim bladders....

 

[d-a]

gills

gills

if you pull it backwards the gills will be damaged and the fish will die through lack of oxygen

 

[Disco Davros]

Really mixed responses on this one it seems. Judging from want I've read here its starting to look more and more like this is one of those questions that isn't totally true but isn't completely wrong either.

Could we then surmise that, if water were to continuously pass the wrong way over the gills that the fish could eventually asphyxiate? But would take an inordinately long time to do so?

 

[jonny_s]

Really mixed responses on this one it seems. Judging from want I've read here its starting to look more and more like this is one of those questions that isn't totally true but isn't completely wrong either.

Could we then surmise that, if water were to continuously pass the wrong way over the gills that the fish could eventually asphyxiate? But would take an inordinately long time to do so?

Possibly might even die of stress first. Oh no have I just added another factor into this scientific debate

 

[Pete from shields]

My dad told me that when i was a young lad, I am nearly sixty now.
He said a fish gets its oxygen from the water through its gills so i reckon if the water is going through its gills the wrong way it would suffocate.

Yeah my dad told me the same thing mate.

Could we then surmise that, if water were to continuously pass the wrong way over the gills that the fish could eventually asphyxiate? But would take an inordinately long time to do so?

I wouldn't say it would take that long maybe 30 minutes depending on species, I would say let's try it but that's opening a whole new can of worms LMAO. Only joking BTW.

 

[codcatcher3000]

well i read sumwer if say sharks are trapped ( somehow) and they cant move forward and stay static they will die...sharks are fish, fish are friends not food than in theory if insufficient oxygen is passing thru the gills fish will dieso if it was dragged backwards with the plats shut then i think i agree with earlier post but how long would be the question

 

[super-MAGuire]

well i read sumwer if say sharks are trapped ( somehow) and they cant move forward and stay static they will die...sharks are fish, fish are friends not food than in theory if insufficient oxygen is passing thru the gills fish will dieso if it was dragged backwards with the plats shut then i think i agree with earlier post but how long would be the question

again, some sharks, nurse sharks G. cirratum for example can sit still and activly pump water over their gills maintaining a flow of water... while i beleive portbeagals and great whites ect have to keep on the ove to maintain the flow of water.

and the fish would die when the levels of o2 are too low to support cell function. Few minutes or so