What keeps sucker fish from cooking to death on glass heaters?

As I understand it, fish do not have a brain anatomy that lets them feel pain. I've read of timid fish taking refuge behind heaters, only to be cooked up. It's as if they don't notice the heat before they became emaciated and powerless to recognize the stressful situation and just swim away.

Today I noticed one of my bristlenose sucking on a heater that was "active". Now that heater can get pretty hot on the glass surface when water isn't washing over it, even though it is in a high-flow area. I was concerned for a few moments before he (or her) hopped off and swam away to his usual spot in the driftwood.

It raised the question in my mind that I've asked myself before: what makes that plec recognize the unsafe situation and swim away, if they feel no pain, at least not pain in the sense that mammals do. And what keeps other fish from recognizing the danger and just cooking to death behind a heater suction-cup-mounted to the glass?

~pH7, Aquarium Ninja

 

Interesting thought. I think that the water constantly moving around the heater keeps the heat tolerable for the fish. But as far as danger receptors go...fish are dumb!

 

haha! Reminds me of...

~pH7, Aquarium Ninja

 

Welcome to the forum

Just because fish don't feel pain as we know it doesn't mean that they don't feel things or process external stimuli. It's a matter of self preservation. I've never heard of a fish cooking hiding behind the heater. the water is only being heated to say 80 degrees, so the heater doesn't get THAT hot. Fish can most certainly feel temperature differences.

Fish hide behind heaters and filters when they are hiding from other fish, so that is a sign of a problem that has to be addressed.

 

Welcome to the forum

Just because fish don't feel pain as we know it doesn't mean that they don't feel things or process external stimuli. It's a matter of self preservation. I've never heard of a fish cooking hiding behind the heater. the water is only being heated to say 80 degrees, so the heater doesn't get THAT hot. Fish can most certainly feel temperature differences.

Fish hide behind heaters and filters when they are hiding from other fish, so that is a sign of a problem that has to be addressed.

Jaysee, it's actually a problem for discus keepers. We have to put our heaters laying down on the bottom of the tank because discus will sometimes fry themselves. In discus tanks, the heaters run at 86 deg F baseline, so heat becomes more of a concern. So yes, it does happen.

Because I'm curious, not because I want to be contrary or mean, may I ask how you "know" that fish feel temperature differences? Where are you getting your facts? I ask because I honestly want to know. Please share your research. I'm hungry to know. I want to read what you're referencing. Please put me on the right path so to speak.

~pH7, Aquarium Ninja

 

Because I'm curious, not because I want to be contrary or mean, may I ask how you "know" that fish feel temperature differences?

I know this isn't directed towards me but fish do feel temperature differences or changes IME. That is why a rapid change in temperature can kill a fish. They just aren't use to and can't handle it. For instance, bettas are tropical fish that like temperatures in the upper 70s.(76-79) When not at this temperature, they can become sluggish and not move at all.

Another instance that might relate to you is about discus. If your discus are use to temperatures around 86, drop your temperature to 76 and see what happens. Ill bet they won't act "normal".

I always thought fish felt pain btw. Interesting.

 

Because I'm curious, not because I want to be contrary or mean, may I ask how you "know" that fish feel temperature differences? Where are you getting your facts? I ask because I honestly want to know. Please share your research. I'm hungry to know. I want to read what you're referencing. Please put me on the right path so to speak.

~pH7, Aquarium Ninja

Fishing. The way to find tuna out in the ocean is to look for temperature breaks in the water. When it's cold, fish will move to shallower water because it warmer. When it's hot, they go deep to where it's colder. There are many examples of how water temperature dictates fish behavior that I've learned in my 25 years of fishing (the last 6 of them as a professional). Of course because their body temps are regulated by the water temp, they are not going to feel "cold". So how can they follow temperature breaks? How can they find that warm spot to sun in if they can't tell that it's warmer? My guess is that they can feel the change in density with the lateral line. Or they must just have internal thermometers and innately know.... so maybe they do "feel" it. Since they are regulated by water temp, it stands to reason that they must be aware on some level of what the temp is.

Oh and changing water temps is a pretty common way to get fish to spawn in an aquarium.



I guess fish can't suffer if they can't feel pain, right?

 

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Oh and changing water temps is a pretty common way to get fish to spawn in an aquarium.

I was also thinking along the lines of activity levels, as well. Cold *tropical* fish slow down, and warm fish move around more.

 

Fishing. The way to find tuna out in the ocean is to look for temperature breaks in the water. When it's cold, fish will move to shallower water because it warmer. When it's hot, they go deep to where it's colder. There are many examples of how water temperature dictates fish behavior that I've learned in my 25 years of fishing (the last 6 of them as a professional). Of course because their body temps are regulated by the water temp, they are not going to feel "cold". So how can they follow temperature breaks? How can they find that warm spot to sun in if they can't tell that it's warmer? My guess is that they can feel the change in density with the lateral line. Or they must just have internal thermometers and innately know.... so maybe they do "feel" it. Since they are regulated by water temp, it stands to reason that they must be aware on some level of what the temp is.

Oh and changing water temps is a pretty common way to get fish to spawn in an aquarium.

Indeed, biologically responding to water temperature changes is NOT the same as being sentient about it, nor is it the same as the lesser order of sensory interpretation: "feeling".

What exactly causes these changes in activity, behavior, etc is what fascinates me. What is it that is causing the biological response, and what sensory mechanism is interpreting the stimuli, whether the reaction in the fish is involuntary, innate, instictive, or otherwise.

~pH7, Aquarium Ninja

 

I was also thinking along the lines of activity levels, as well. Cold *tropical* fish slow down, and warm fish move around more.

But that's a physiological effect, not a behavioral one. Their metabolism speeds up or slows down. Fish in our tanks don't have a choice in that matter about the temp. Wild fish do, and as an expert in finding wild fish, I can say with certainty that they choose to be in certain temperatures, and that the temperature often dictates their movement.

 

But that's a physiological effect, not a behavioral one. Their metabolism speeds up or slows down. Fish in our tanks don't have a choice in that matter about the temp. Wild fish do, and as an expert in finding wild fish, I can say with certainty that they choose to be in certain temperatures, and that the temperature often dictates their movement.

So if your saying that if I gave fish the opportunity to choose what temp they want and to do so connected two tanks together with a tube and one tank had a cooler temp than the other, the fish inside would choose and prefer one tank over the other? Stay in one tank instead of going to the other different temperature tank?

 

Indeed, biologically responding to water temperature changes is NOT the same as being sentient about it, nor is it the same as the lesser order of sensory interpretation: "feeling".

What exactly causes these changes in activity, behavior, etc is what fascinates me. What is it that is causing the biological response, and what sensory mechanism is interpreting the stimuli, whether the reaction in the fish is involuntary, innate, instictive, or otherwise.

~pH7, Aquarium Ninja

First off, no one said anything about being sentient. Also, that's not a requirement for feeling. You don't have to be "conscious" of external stimulus in order to respond to it. The applicable definition of feeling is perception by touch - fish have a lateral line to detect changes in the water that is touching them. Ipso facto, fish feel.

Perhaps you can explain why responding to water temperature changes doesn't prove that they can feel the difference.

So if your saying that if I gave fish the opportunity to choose what temp they want and to do so connected two tanks together with a tube and one tank had a cooler temp than the other, the fish inside would choose and prefer one tank over the other? Stay in one tank instead of going to the other different temperature tank?

Yes, If one side were 75 and the other 85, and you had discus in the tank, they would all be in the warm water.

Changes in water temperature are what initiate migrations.

 

I always thought fish felt pain btw. Interesting.

Nope, fish don't have a neocortex Neocortex - Wikipedia

You need one in order to be "conciously" aware of stimulI that "hurt". However there is a general scientific consensus that fish expierience nociception, which is basically saying that they can and do respond to painful stimulI without being conciously aware of it. See Nociception - Wikipedia

~pH7, Aquarium Ninja

By way of follow up to my previous post, with regard to nociception references at wikipedia: "Nociception can also cause generalized autonomic responses before or without reaching consciousness to cause pallor, diaphoresis, tachycardia, hypertension, lightheadedness, nausea and fainting."

This basically means that you can lose your color because of a noxious stimulation and not know or feel it consciously. Yes, your body had to feel and recognize autonomically that something was wrong or it wouldn't have become pale, however you didn't know it happened in this example.

Ipso facto, yes, fish autonomically respond to noxious (e.g.- painful) stimulI via nociception.

For the record, there are still some academics who hypothesize (without much proof, other than that which satisfies themselves), that fish can "feel" conciously because they *might* be able to use part(s) of their very limited brain physiology to perform lower order functions of a neocortex. Again, this is not proven, nor is it globaly recognized as an even viable theory.

~pH7, Aquarium Ninja

Yes, If one side were 75 and the other 85, and you had discus in the tank, they would all be in the warm water.

Changes in water temperature are what initiate migrations.

Actually, wild discus live in temperatures that are not that high. The short answer to this is that we don't know until we try it, and even then, the same fish won't do the same thing under the same conditions from one day to the next. It would take multiple experiments to determine preference, if it could be determined at all. Discus aren't migratory creatures, and would probably *not* move to warmer water due to a migratory instinct; if they moved, it would more likely be because they wanted to be in water that their bodies had grown accustomed to in order to relieve the stress on the body that temperature changes can effectualize. It would not be due to mental suffering.

We only keep discus at higher temperatures domestically because it's easier to manage disease and metabolic response (eating, primarily). When you want discus to breed, you put them in a more "native" environment. That means softer water, and lower temperatures, and almost no nitrates at all. Huge daily water changes are mandatory if you want to get healthy, non-stunted hatchlings.

~pH7, Aquarium Ninja

 

I don't know to what degree but fish do have some receptors to pain. Otherwise how would you explain the scratching against decorations when they have ick?

 

To summarize and clarify the last several posts in layman's terms...

1) I agree that fish do feel things!
2) There is a fundamental difference in the way that fish feel things, and the way that we do.
3) The original question remains unanswered: what keeps my sucker fish from sticking to and sucking on my glass heater all day

And now abandoning layman's terms, I will attempt to explain the answer I believe I've found:
I hypothesize based on the extensive reading I've done in the last three hours that my pleco reacts to stimulI from its nocireceptors--primarily pesent in the nose/mouth region--after the nocireceptors have informed its brain via its central nervous system of the stimulus; the brain then (through a series of chemical reactions) illicits the fish's limited and non-emotional "aggression" reaction and the fish swims away until its "feeling" of the temperature-based stimulus has diminished

I didn't plan on coming up with that answer. Indeed, when I initially asked, I had no idea. It was due to the mildly contentious tone of this discussion that I decided to go it on my own and finally turned up what I consider a factual, scientifically-backed answer. Go ahead and flame me for it if you must.

Thanks to all who inspired me. I'm glad to have made your aquaintences.

May I also say, Jaycee, that over 11K posts is an incredible accomplishment. It makes me think about all thousands of times you helped a fellow hobbyist. My hat is off to you.

~pH7, Aquarium Ninja

 

Ipso facto, yes, fish autonomically respond to noxious (e.g.- painful) stimulI via nociception.

We are discussing sensing temperature changes in the water, not responding to noxious stimuli. I fail to see what one has to do with the other.

That's good to know about the discus - I want to keep them but I don't want to keep the tank that warm. Everyone I know that keeps them has advised against it though.

I did not claim that discus were migratory fish. The extra line separating the last sentence denotes a new subject matter. In hindsight perhaps I should have used 2 or 3 lines of separation. I was providing another example of how changes in water temperature influence behavior.

You seem to be hung up on this notion that you must be aware of the fact that you are receiving stimulation in order to feel the stimulation. I'm attributing a more basic sense of the idea of feeling because of the primitive nature of fish. It seems a bit silly to expect more from such an animal.

NO WHERE has mental suffering of any kind been brought up as a motivation for anything, so I don't understand why it's being brought up now.

You wanted to know how I knew that fish feel temperature changes. I provided numerous examples based on many years of practical observation and hands on experience. I'm not going to argue about the quality of the feeling the fish has. Discussing such things without agreeing to a standard is a waste of time.



To answer your original question, sensory perception triggers instincts of self preservation that prevent the pleco from cooking to death on the heater.

By the way, if your pleco doesn't have bristles on it's head, it's a female.

 

We are discussing sensing temperature changes in the water, not responding to noxious stimuli. I fail to see what one has to do with the other.

*timidly points to wikipedia link about nocireception*

Temperature is defined as one of the noxious stimulI under heading "Nociception in non-mammalian animals". As others have noted, and as I'm sure you know, large temperature swings can prove fatal, and therefore by classification are a noxious stimulus, at least according to scientists...

Please also see my (last) summary post in order to clarify what you seem to perceive is an inability on my part to contrast the difference between feeling something and being conciously aware of the stimulus. Somewhere along the way you didn't realize I've been agreeing with you.

~pH7, Aquarium Ninja

 

*timidly points to wikipedia link about nocireception*

Temperature is defined as one of the noxious stimulI under heading "Nociception in non-mammalian animals". As others have noted, and as I'm sure you know, large temperature swings can prove fatal, and therefore by classification are a noxious stimulus, at least according to scientists...

I never mentioned a thing about large temperature swings killing fish. I think all of the examples I gave were of small temperature changes.

Please understand that you posted your summary while I was typing so I didn't have a chance to read it before posting. And know that we do not flame people here.

I obviously misinterpreted your position if we are in agreement.