[lestatak]

This may be a dumb question but how do fish know they are of the same species?

 

[Number6]

It's not a dumb question at all... but the answer is going to seem strange!

They don't know that a fish is the same species or not. They don't think about it at all... they simply pick a mate that is like themselves, but not too much alike, but also not very different at all.

Some individuals prefer a mate more like themselves, while others want something a little different. Problem is, inbreeding and outcrossing can be very risky (see inbreeding depression and outbreeding depression). So the fish that like mates that fit the balance point between like and not like are the ones whose kids live to pick a mate...

it only gets more complicated from this point onwards in the conversation, but that should give you food for thought!

 

[Shwaine]

Fish are a whole lot brighter than we humans give them credit for. It's even been recently proven that fish can count up to 4 (http://www.loveearth.com/us/blog/news25february2008). There are certain signs a fish can use to determine species such as coloration and behavior. Think of these as the fish's form of language. Think about it for a moment and think how both the color and behavior of a fish changes when it is stressed or looking for a mate. This is not by accident. It's all part of how they communicate with one another. Read this article for more info: http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2008/02/20/scifish120.xml

 

[Number6]

There are certain signs a fish can use to determine species such as coloration and behavior.

There is no way that fish can apply logic at the level you are suggesting... there is no way for a fish to look at, smell, or communicate with another fish and say yup, you and I belong to the same gene pool. Mate selection is an instinctive behavior. What stimulus is recognized varies from color to smell etc. but there is no intent on the part of the fish.

 

[Leviathan25]

but there is no intent on the part of the fish.

I aggree, but theres some strong instinct in some, and the smell and sight must have alot to do with that instinct kicking in, I have a nice mixed 125g stup and whenever I add a female to the mix, almost immediately like some one rang a bell ,the male of the same species zooms like lightning to her and starts his fanning and "I like you chasing", this have happened numerous times.

 

[lloyd]

..."tasks closely resemble what we found in pre-verbal organisms such as fish!"

...what the heck is a 'pre verbal' organism? -perhaps in another 2 billion years we will ask our fish about water parameters, have them hold elections to digress conspecific aggression levels...maybe even vacuum their own substrate? :dancing:

 

[Number6]

but there is no intent on the part of the fish.

I aggree, but theres some strong instinct in some, and the smell and sight must have alot to do with that instinct kicking in, I have a nice mixed 125g stup and whenever I add a female to the mix, almost immediately like some one rang a bell ,the male of the same species zooms like lightning to her and starts his fanning and "I like you chasing", this have happened numerous times.

Smell and sight have tons to do with mate selection.
I give fish all credit for picking great mates... but it has nothing to do with an instinct to pick from one's own gene pool and everything to do with picking the most attractive that is available with predetermined resistance to individuals that are too similar and dissimilar because of the decline n mean fitness associated with inbreeding depression and outbreeding depression.

In other words... "species" is an accident of each individual mate selection choice and the selective pressures of the time.

 

[Leviathan25]

but there is no intent on the part of the fish

following this to be true
the next 2 quotes seem like a contradiction

Smell and sight have tons to do with mate selection

but it has nothing to do with an instinct

and I understand what your saying the following paragraph but many
have completely different looking mates, and most hybrid situations usually
occur when there are none of their own readily available(but not always, I know)

 

[Number6]

Here's an incredibly simple experiment but an effective one.

Take female cichlid of any species... raise it alone from a wriggler.

Now put the adult female into the middle compartment of a three way separated tank with a male of her own kind on one side and a different species male on the other side.

Female obviously picks the male of her own kind despite having never seen her own kind. Why?

She has no criteria to allow her to logically deduce sameness to herself... so how did it happen?

Now thwart her ability to pick her own kind... place a male somewhat like her but not the same species... she'll pick him as well over the dissimilar.
Why?

Simple... it's an instinct to pick for sameness to a degree predetermined by what was selected for in prior generations.

Species is just the genetic isolation that happens as an accident of this instinct at the individual level.

 

[Leviathan25]

Simple... it's an instinct to pick for sameness to a degree predetermined by what was selected for in prior generations

aggreed, but also sounds like what I was saying, as now your saying it is instint
vs's saying

nothing to do with an instinct

p.s. not trying to be frustrating, I find this very interesting and knowledgable

 

[Number6]

Cutting a sentence can often change the meaning... if you reread the original and grab what I meant as the full thought:

but it has nothing to do with an instinct to pick from one's own gene pool

So I'm not saying it "has nothing to do with instinct" but saying "an instinct" meaning the hypothetical one where fish could id another fish as part of it's own gene pool.

One could view my point as being "just a semantic" argument... but I think it is very useful to know how mates pick each other so we can relax a bit about inbreeding and try to accept a better balance point in our cichlid gene pools...
if more people bought half siblings, cousins, etc. and did less outcrossing at random, I firmly believe we'd have healthier fish available to us all!

It also explains to us why some fish will hybridize more willingly than others.

I personally find that info very handy.

 

[Shwaine]

There are certain signs a fish can use to determine species such as coloration and behavior.

There is no way that fish can apply logic at the level you are suggesting... there is no way for a fish to look at, smell, or communicate with another fish and say yup, you and I belong to the same gene pool. Mate selection is an instinctive behavior. What stimulus is recognized varies from color to smell etc. but there is no intent on the part of the fish.

Who said anything about logic? How else is a fish supposed to have input for mate selection if not by coloration and behavioral clues? Did you bother to read those articles I posted or just went off on your own personal diatribe? There is a level of cognition occurring that you seem to want to gloss over with a simplified description of mate selection.

Really, if I wanted a reguritation of the standard simplification of mate selection that's spewed in college biology, I'd have signed on as a biology teacher. Besides, I did not read the original question as asking "how do fish select mates" but rather as "how do fish recognize conspecifics". Conspecific recognition goes beyond mate selection to include territorial disputes, shoaling/schooling behavior and other similar behaviors. Such behaviors are mediated by behavioral signs and coloration. There is far more detail to the cognition occurring than what would be covered in a college course unless you are pursuing a graduate degree in behavioral biology.

The fact that a shoaling fish can tell the relative size of shoals in order to choose the larger one should tell you that there's cognition occurring at some level. Even "instinct" implies cognition, although of a more static than dynamic nature. But really, in order for any action to be taken, whether you wish to attribute it to hard-wired instinct or to rudimentary reasoning still has to take external stimuli and some sort of language to describe the external stimuli. Note that a language in this sense is just an ordered, consistent method of categorizing stimuli. It is not a language in the sense of a human natural language with communication of complex thoughts. It is just a set of rules with which to interpret the environment.

 

[Number6]

Regardless Shwaine, whether you are talking about mate selection or any other behavior, the fish are not as self aware as you seem to give them credit. I read the articles, and I do not see that they back you up at all...

I think on this one, you and I will have to agree to disagree. Fish, and even cichlids, are relatively simple brained animals...

 

[Leviathan25]

Nobody needs to get their knickers in a twist, it's just an informative thread which none of us started in the first place, and the phrase "aggree to disaggree" is just kids way today of saying "whatever" Lets look a little further in this, I'm starting to lean more towards Shwaine's point as far as awarenees goes, read this article I found. Now Number6 every point you made was acurate but as he said, slightly detoured from the original question. Now lets be objective and read this.

Self awareness is proven by the many behavioral patterns which animals exhibit which suggest, without the shadow of a doubt, the possessions of certain mental stimuli; some of which are: status, pride, self esteem, territoriality, self punishment, self love, supremacy, and submission.

As an example lets take supremacy and submission: supremacy and submission are feelings which can not exist without self awareness, for if you are not aware of yourself, how can you be able to understand how great you are or how small you are.

Supremacy and submission are emotions which exists in fish, reptiles, mammals and birds. The reason why it exists in so many animals is because, along with territoriality, it is the most primitive of all feelings within self awareness.

It is my belief, that the sense of self awareness might have evolved as the by-product from some of the senses of self preservation, such as supremacy and territoriality. In other ways, when you evolve these adaptations, which are neurological, instinctive factors in the brain, what you get as the by-product of such, is the primitive self awareness which is present in fish as well as reptiles. Samuel Vergio Miensinompe

 

[Number6]

and the phrase "aggree to disaggree" is just kids way today of saying "whatever"

Not at all... at least that is not how I intended that line...
one can look at a behaviour such as territoriality and see a fish chase off another competitor and assume that the fish is saying get out of MY space, but this is an assumption of self awareness that the fish may, or may not have.

The conclusions that I can take away from both articles linked to is that there is such a thing as behavior that crosses species boundaries and elicits a reaction in other individuals. There is NO information in those articles that talks about the self awareness and logic required (yes logic) for the individual to recognize that it is the same as a much larger group of animals.

So when I read the original question:

This may be a dumb question but how do fish know they are of the same species?

It is specifically asking about awareness of species... it is NOT asking about Conspecific recognition... which of course I am fully aware of and in fact, pretty much said in ALL my replies.
It is talking about recognizing that it is one of a larger group of individuals that we label species.

It is the next step where Shwaine and I split miles apart from each other... I say that they have NO awareness of this larger group of individuals and will react to anything like them regardless of how related they may be.

Those of us who mix lakes and continents in our aquariums can attest to the fact that fish react with the same reactions towards very unrelated conspecifics in much the same way as they react to more closely related cichlids. What we also see is that cichlids react MORE to a similar but less related individual than they do to a more closely related but very very different looking individual.

Why I suggest that Shwaine and I agree to disagree is that with no proof of self awareness beyond a primitive self awareness, and no proof that cichlids lack this self awareness, then Shwaine and I are both firmly in the realm of belief and assumptions.

We have to agree to disagree... either that, or we have to go into some HUGE debate about the level of self awareness in cichlids....

That is something that I doubt can be solved on this thread since animal behavior specialists argue about that on a constant basis.

So I am not trying to be dismissive... I just recognize that her opinion is probably as valid as mine, so we need to drop it.

 

[Darkside]

Fish can count up to 4. Fish react to the stimuli of their environments in a predetermined way. Fish do not apply logic to changing situations, presented with the same situation, they will always react in the same manner. Therefore, fish do not show a high level of intelligence.

 

[Hoggy Boss]

It's late in the workday and I have to use a dictionary to understand most of the previous post. Simple answer it's all about the "shakes & wiggles" in my opinion.

 

[PsYcHoTiC_MaDmAn]

I drag an old thread up

found an interesting read just now. based on studies on Mbuna, though why their still calling the Pseudotropheus Zebra is beyond me, would have thought that the scientists would use the correct name for it...

http://www.practicalfishkeeping.co.uk/pfk/pages/item.php?news=1650

 

[naegling23]

let me add my 2c here.

If I float a bag with a new fish in the tank, the related fish in the tank will recognize it as a mate. So, pheromones may be passing through the bag, but that is unlikely, so it might be a visible cue, and looking at the bewildering variety of colors and patterns, that seems a likely explination. The fish are likely looking for mates that have attractive patterns. Of course attractive would be hardwired to anything similar to themselves. Also, just because we see one color/pattern on the fish does not mean that the fish sees the same one. Have you ever seen UV photographs of flowers? This is in the visible spectrum to a bee, and it looks like nothing that we are used to seeing. It is certainly possible that fish can detect UV or IF wavelengths, and get a different picture than we are used to seeing.

 

[vfc]

Fish can't see themselves; they have no idea what color and shape they are. It must be hard wired for them to recognize their own kind.