Questions relating to the study of fish.

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Fish and microplastic particles

How does exposure of fish to microplastic particles decrease egg-hatching and give young fish a craving for them? From Garbage in, garbage out: marine plastic 2016-06-24 | Espresso There is more ...
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do fishes come to die in beaches? [on hold]

Afternoon I found a fish in a beach, it seems that it kept moving, i was not injured but suddenly stop moving and 'died' so my question is do fishes sometimes come to day at beaches ?? or what could ...
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1answer
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Why is flash light harmful to what aquatic life forms?

When visiting an aquarium, it's often not allowed to take photographs with a flashlight on. It is said that the flash light with very high intensity is harmful to the displayed life forms. I respect ...
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What drives male fish to spray their milt?

In mammals the sexdrive of the males is because the intercourse provides a satisfaction where after, the sperm is ejaculated into the female. However, the male sperm doesn't enter the female fish but ...
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1answer
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What Freshwater Fish Are Affected By Magnetic Fields

I am interested in knowing which freshwater fish are affected by magnetic fields. I've heard that Lake Sturgeon are, but would like more references. This is for a project that will have buried 3 ...
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Why do fishes have both a gustatory and an olfactory system?

I would like to know if there is a know reason for which fishes (and many aquatic species) have both an olfactory and a gustatory system. As far as I know, in all fish species the chemoreceptors, ...
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1answer
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Capture recapture for only two visit assuming a open population model

I have a study system where I’m doing a capture recapture analysis. I mark fish in one year and I’m recapturing a subset of them the next year. I only have 2 capture events. Since a lot of time has ...
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Do any fish have to hold their urine in deep water? [closed]

I know this is going to sound really weird! But I was confronted with this claim and the person strongly had faith in it! I said faith since he couldn't provide any evidence. Is there any kind of ...
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How can a tongue-biting parasitic arthropod become a fully functional tongue?

From wikipedia: The parasite Cymothoa exigua [consumes a fish's tongue and] then replaces [it] by attaching its own body to the muscles of the tongue stub. The fish is able to use the parasite ...
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How many kg of algae does a kg of shiners or minnows consume to reach about 3"? [closed]

The title pretty much sums this up. I'm trying to determine how much algae mass is required to produce some mass of shiners, minnows, etc (small fish no more than about 3 inches) - unit conversion ...
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1answer
54 views

Sexing fish from a tissue sample

I am a member of a local fish club, we have a lot of different aquarium fish and would like to trade them amongst us. We all have a few fish that don't form pairs and would like to see if they pair up ...
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1answer
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Why do raw prawns turn red after sitting in vinegar?

Yesterday morning I put some raw prawns (shell removed) into vinegar (more specific this one), and put them in fridge. When I came back at night all of them turned red, which looks cooked, except ...
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Are the cells (structures) of deep sea fish different? And can they survive in shallow water?

In the deep oceans the pressure is enormous. But still there are fish living. But are the cells of them different from fish who just live at the surface of waters? For example, are the cells smaller ...
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Do fish increase or decrease pH of aquarium water?

If I understand it correctly, aquarium fish produce NH3 as their waste product and CO2 due to respiration. Producing NH3 increases water pH due to its equilibrium with NH4+. Producing CO2 decreases pH ...
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Why is there a difference in the rotation of the tail fin in fish compared to marine mammals?

I've been thinking about this one, but I can't seem to find what causes this difference. All fishes that I've seen have their tail fin positioned vertical: But all the marine mammals I know have ...
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Does anybody know what this shark is eating?

Looking for a species identification on the orange fish that the shark is eating. The shark is a goblin shark filmed as part of the BBC's 'Legends of the Deep: Deep Sea Sharks'.
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How many fish are there? [closed]

I am trying to research the estimated population of certain fish throughout time. The fish I cannot seem to find out what I want to know are: Tilapia; Trout; Salmon; Tuna; and Anchovies. Sources that ...
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1answer
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Do saltwater fish need to drink? [duplicate]

In my biology class we got the question if saltwater fish need to drink. We need to use the term osmosis, but I cannot think of a valid answer and we were allowed to ask help.
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Are there predators evolved to eat puffer fish?

Puffer fish is known for having a anti-predation defense mechanism of having toxin-exuding spikes. Are there predators which evolved specifically to prey on puffer fish? (presumably, by evolving ...
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1answer
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Why isn't the biological niche occupied by whales instead occupied by fishes?

As by the title. Why aren't there many more, and larger, whale shark like creatures instead of the great mammalian swimmers? I'd assume fish have a benefit in doing the whole "being under water" thing ...
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Are there fishes with a double circulatory system?

Our courseware materials say there are such fishes, but my Internet searches suggests fishes only have a single circulatory system.
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967 views

Why have whales and dolphins not evolved to have gills?

It seems at first glance that it would be an evolutionary disadvantage for a sea creature to have to come up to the surface on a regular basis in order to breathe, so why are there animals (e.g. ...
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1answer
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Biological Evolution outside of Earth [closed]

What drives evolution forward? I heard that climate change drives species to evolve and adapt. Is there any other mechanism that is encoded in our DNA by which species can over abrupt changes, evolve ...
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1answer
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How does this headless fish still move?

There is a (VIDEO) on Facebook where the fish starts to flail around despite no heart or internal organs. What causes the fish to flail around the way it does? My theories: It is because of ...
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3answers
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What is this fish?! Is it even real?

According to a guy in a Facebook group I belong to, this fish was caught in the Missouri River near Omaha, NE, US. I have never seen one like it in my life, not in person or photo or anywhere. What on ...
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1answer
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why do marine organisms orient with their bellies facing downwards?

why do marine organisms orient with their bellies facing downwards (like most creatures) given that they have relatively fewer constraints on their orientations than land or air organisms?
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Best tail for swimming?

I understand that the vertical tails of fish and the horizontal flukes of cetaceans evolved due to the spinal movements of their ancestors but I was just wondering which was the most efficient for ...
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Are fish roe unicellular?

Are roe (fish eggs, caviar, etc.) single cells? I have tried looking this up on google (sadly, to no avail), and I am guessing they might be multicellular (like bird eggs) or consist of one cell plus ...
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359 views

Do rare earth metals actually repel sharks? [closed]

Stroud claims that sharks are effectively repelled by the use of rare earth metals in the water. There has even been a patent issued by the same author for rare earth-wrapped fish hooks to reduce the ...
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About sharks and how they find fish

Other than olfactory senses do sharks use some kind of sense that uses electromagnetic waves? Is this similar to an electric eel? I saw a book with the cover statement 'Sharks never get cancer'. IS ...
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1answer
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What happens when someone is stung by a jellyfish?

What happens in the human body when someone is stung by a jellyfish; namely a box jelly. Judging by what I have heard about the stings I'm guessing that they involve a neurotoxin. But what is ...
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1answer
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Help needed in fish identification

Please help me identify these fish. I looked around but wasn't able to determine its species.
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How to differentiate between similar looking carps efficiently?

Carps look almost the same (e.g - Rohu, Catla). So, is there a specific distinguishing set of characteristics to help determine their species just by looking at them from afar (or maybe in some other ...
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What evolutionary advantages are provided by ovoviviparity?

I read that some sharks are ovoviviparous. What advantages and disadvantages are provided by this type of reproduction as opposed to egg laying and live birth?
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What fish (and/or shellfish) species with a multi-year life-cycle, besides salmon, die after spawning?

Most species of salmon die after spawning. Are there any other types of fish that spawn once and then die after a multi-year life-cylce? Is this a rare life history strategy among our human exploited ...
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1answer
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How does anadromous fish physiology “know” to switch from salt to freshwater and back?

What mechanism allows anadromous fish (like salmon) to switch from salt to fresh water and back? How does the fish "know" to switch its physiology and do other fish possess the biochemical machinery ...
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How do you accurately measure anguiliform (eel) locomotion?

In one of my courses, we were discussing a paper by Muller and van Leeuwen (2006) which made a lot of comparisons the differences between carangiform (mullet) and anguilliform (eel) locomotion. While ...
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Why don't fish groom each other?

Fish are often plagued by external parasites, which are presumably difficult for them to remove. There are well known cases where large fish come to coral reefs and allow smaller fish to pick off ...
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How do fish communicate?

Fish, as far as I know ( of course there may be exceptions) , don't have any vocal organ...but they are proven to be social...so how do they manage to communicate with each other...on land, organisms ...
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Effect of Ethanol on Brain Volume Measurements

I want to compare the brain sizes of two populations of fish. However, all the samples I have were fixed in 95% ethanol. As far as I know, 4% formalin is the normal fixative for soft tissues. Can I ...
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Can you get enough water by eating only fish?

Scenario: In a boat in the middle of the sea, no freshwater or food stores, no desalination equipment, no rain, but you can catch fish and eat it raw. Can you get enough water this way to survive, let'...
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Do river sharks (genus Glyphis) have reduced rectal glands for salt removal?

Do river sharks of the genus Glyphis have reduced or absent rectal glands for salt removal?   The rectal gland of marine sharks removes excess salts to maintain osmotic balance (Oguri 1964).  In ...
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In practice, do fishes die from old age?

I was watching sea birds eating fishes and wondered if fishes actually died from old age, or if they are all eaten before this can happen? I reckon some big predator fishes must be able to live long ...
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harvesting fertilized eggs from Tetraodontidae species?

I would like to know how easy/difficult it is to harvest fertilized eggs from Tetraodontidae species such as Tetraodon nigroviridis or Takifugu rubripes compared to zebrafish? Ultimately, I would like ...
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Is vision a vestigial sense for deep ocean species?

Sunlight doesn't penetrate beyond a couple of hundred feet from the surface of the ocean. Species that exist at greater depth probably live in a state of perpetual night; yet from a quick google image ...
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Why is clownfish attracted to actinia?

I heard that Actinia Equina normally eats what it can catch, but this clownfish here doesn't care much about that: https://www.youtube.com/watch?v=Ughm4mnZ1ls Since the actinia obviously can't hold ...
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1answer
178 views

Identifying internal structures of dissected fish

Note : Images displayed below might be disturbing to some people. I have dissected a fish for the first time ! I have some idea of what some of the structures might be but I am not sure and so would ...
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How does a stonefish get oxygen out of water?

It is said that the stonefish (Synanceia) is able to stay out of the water for up to 24 hours. I wonder how they get oxygen from the air. Could someone explain this?
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Why does temperature shock kill fish?

As is advised with most fish you should avoid sudden changes in water temperature (for example by introducing new water that hasn't been left to come to room temperature). I have, however, never ...