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Can Fish Swim Backwards?


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#1 steven :)

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Posted 28 March 2006 - 03:29 PM

i was wondering can fish swim backwards? cus some of mine can :S also some of the fish seem to be breathin quite fast i was wondering if that is normal? thnx

#2 JonDawg

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Posted 28 March 2006 - 03:30 PM

i know swordtails can swim backwards, very quickly at that

#3 Phoenixfish

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Posted 28 March 2006 - 03:31 PM

ive heard that sharks cant they suffurcat or drown or something

#4 steven :)

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Posted 28 March 2006 - 03:32 PM

i know swordtails can swim backwards, very quickly at that

my sword tails are fine i was just wondering if they was il

#5 blitztidus

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Posted 28 March 2006 - 04:09 PM

If the fish are breathing that fast, is their enough bubbles in the tank for them to breath in?

#6 andrewp

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Posted 28 March 2006 - 05:06 PM

I have an elephant nose that seems to be able to manouvre its self backwards

#7 andywg

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Posted 28 March 2006 - 06:02 PM

If the fish are breathing that fast, is their enough bubbles in the tank for them to breath in?

Most fish can't breathe air from bubbles and obtain oxygen from either passing water over their gills, or through taking air on from the surface and utilising internal organs.

bubbles are not great for oxygenation as they are not in contact witht he water long enough to allow a gas exchange. They create some surface agitation to aid gas exchange, but this is far better achieved through the placement of a powerhead or a filter outlet.

#8 steven :)

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Posted 28 March 2006 - 06:20 PM

thnx 4 ur comments my guppy is gona give birth soon :d:D:d:D:D

#9 Iron Man

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Posted 28 March 2006 - 06:20 PM

When I first put my Silver Dollars in the tank...they did both of those things!

They would slowly go through caves to see if they could fit, and if not...would slowly and carefully back out. Also..they were really panicked when first letting them out into the tank (Silver Dollar just naturally panic over things) and I've never seen fish breathe so hard.

But if your fish have labored breathing all the time something is wrong with the oxygen consentration in your water....or you might have a sick fish, or both.

#10 fish mad

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Posted 28 March 2006 - 07:56 PM

When I first put my Silver Dollars in the tank...they did both of those things!

They would slowly go through caves to see if they could fit, and if not...would slowly and carefully back out. Also..they were really panicked when first letting them out into the tank (Silver Dollar just naturally panic over things) and I've never seen fish breathe so hard.

But if your fish have labored breathing all the time something is wrong with the oxygen consentration in your water....or you might have a sick fish, or both.

guppies can to try and impress the female

#11 Bignose

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Posted 28 March 2006 - 10:26 PM

Fish swim by passing a wave through their bodies. In 1960, Lighthill showed, in some simplified analysis, that in order for a fish to move at speed x, the wave in their bodies has to move at speed (5/4)x.

What is really interesting is that in this analysis, the fish is treated as just a flexible line, what that really means is all the fins, including the tail, are not needed for locomotion. There are a few species of fish that are pectoral swimmers, but most fish use oscillations. In fish, they are side to side oscillations, dolphins use up and down oscillations.

Finally, back to the original question, sure fish can swim backwards. The analysis by Lighthill does not presuppose a direction. All the fish has to do is make the wave travel in the opposite direction along its body.

#12 dgwebster

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Posted 28 March 2006 - 11:05 PM

my gouramis swim backwards

with "breathing" alot (looks more like alot of gasping) i had one bad incident at the start of my aquarist hobby that turned out to be mouth fungus.

however, common ones are temperture too high, resulting in lower oxygen content in the water for the particular species or not enough surface agitation to promote carbon/oxygen transfer.

Upon saying that, my female gourami breathes alot more regularly than any of my other fish, inc the male gourami but seems in perfect health, has been for 2 weeks now. so im no longer worrying so much. i continue to watch though for any changes. though he is causing a more pressing moment by stealing my plants and taking them into a cave to munch on *grr*

#13 Jules H-T

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Posted 29 March 2006 - 11:12 AM

The degree of the ability to go backwards (and willingness to do so) is going to depend on the species, and the level of the species' requirement to go backwards in it's natural environment.

It would seem on the surface of it like a bit of an evolutionary mistake to have absolutely no way at all of going backwards- one wrong turn and it'd be the end of you! There might be a fish somewhere that 100%can't though. Anyone?

@ Bignose, that's very interesting information!

On the topic of oscilliatory (sp?) vs pectoral swimming, and purely from my own observation, it seems to me that most fish in the aquarium trade are incapable of reversing the oscillations along their body (presumably due to muscle structure), and do resort to pectoral swimming (or at least a combination of the two methods) in order to reverse- the knife fish being an obvious exception, and they do spend as much time going in one direction as the other.

Edited by Jules H-T, 29 March 2006 - 11:15 AM.


#14 the man from atlantis

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Posted 29 March 2006 - 11:23 AM

Bristlenose cats can kinda wiggle backwards(it's swimmin jim, but not as we know it) and clown loach seem to be able to swim backwards ,upside down , at 45 degree angle , inside out, you nome it

#15 prankster705

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Posted 29 March 2006 - 11:30 AM

Hmm, some can, some can't. I know glass catfish can (at least mine did), quite good at it, many others can tho (some better, some worse). Sharks can because they have to keep moving forward or they suffocate.

#16 andywg

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Posted 29 March 2006 - 12:07 PM

Only "ram fed" sharks prank (i.e. those that only pass water over their gills by movement).

A notable exception is the nurse shark which has a habit of sitting on the bottom as it has an ability to pass water over its gills without needing movement. There are a number of other species whcih share this trait.

(ps: I assumed by "sharks" you meant those of the Elasmobranch Order, rather than the Cyprinids often refered to as sharks)

#17 Jules H-T

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Posted 29 March 2006 - 01:08 PM

Only "ram fed" sharks prank (i.e. those that only pass water over their gills by movement).


I accept this is the prevailing opinion, but I do seem to recall seeing a David Attenborough documentary some time ago that dispelled it as a myth that there were sharks that died if they stopped moving completely (or at least disproved it for some species traditionally accepted as being in this category). It showed footage of sharks previously though to never stop, sitting there doing nothing (not even holding station against a current) for prolonged periods. Whether they just conserved oxygen for a few hours I don't recall.

Perhaps someone else will remeber this as I have no details. Might have been part of the Blue Planet series, might not.

#18 Bignose

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Posted 29 March 2006 - 09:08 PM

@ Bignose, that's very interesting information!

On the topic of oscilliatory (sp?) vs pectoral swimming, and purely from my own observation, it seems to me that most fish in the aquarium trade are incapable of reversing the oscillations along their body (presumably due to muscle structure), and do resort to pectoral swimming (or at least a combination of the two methods) in order to reverse- the knife fish being an obvious exception, and they do spend as much time going in one direction as the other.



Yes, the math from the 1960's was a very simplified analysis. No consideration of muscle structure at all. In one of Prof. Lighthill's very next papers he introduces a better description of the wave. In the first paper, it is assumed that the entire fish oscillates with the same amplitude. Specifically, the amount the head goes back and forth is exactly the same as the tail. This is not true for most species, really only eels and maybe the knife fish. The next paper used an exponentially increasing sine wave... the head moves only a few percent of what the tail can move. This puts an implied direction in swimming movement now, though mathematically it is still possible to swim backwards. However, it is most likely just as easy to turn around, especially in case of emergency.

Here is where the different muscle groups come in, as well. Most fish have at least some white burst muscles. The white muscles can be activated very quickly for immediate bursts of speed, but cannot be used for very long. But, these white muscle groups are just for escape (or lunging at prey) so, if a fish can activate them and turn quickly and then swim head-first, that is probably preferred to awkwardly swimming backwards. Also, there is at least one practical consideration: the fish can see better what is in front of them rather than behind.

#19 andywg

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Posted 29 March 2006 - 09:26 PM

Can't find much on that, ecept for the fact that some sharks that are ram-ventilated seem to sit still in front of freshwater caves and the like where the flow of the freshwater is enough to provide respiration (as well as a possible benefit against parasites).

You have to remember that sharks are not bouyant, they are heavier than water, they have no developed gas bladder (such as teleosts, or "modern" fish) which is why the bones are made of cartilage (bone has an SG of around 2, cartilage around 1.2 IIRC). If a shark stops swimming it sinks to the bottom. If it has no way of getting water to pass over the gills it will suffocate.

It may well be that there are some that were thought of as ram-venitlaters are in fact not (perhaps through an ability to pump water across the gills in the short term) or have different ways of doing it (sitting in front of water currents).

#20 dgwebster

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Posted 29 March 2006 - 11:24 PM

i recall that show myself, and they were using cave and labrynth structures which even in the stillest had a small current which they used - it solved the question of why they all faced the same way inside it :) however it efectively allowed them to stop swimming and nature breath for them




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