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Is it true that goldfish don't have stomachs?


happysnapper

I guess the title says it all. Is it true?


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  • Regular Member

I guess the title says it all. Is it true?

Or you could say that they are ALL stomach :rofl

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  • Regular Member

For sure! Well, I guess if they don't have a stomach that would make sense why they are such Greedy McHungertons. Nowhere to store the food = EAT OMG EEEEAAAAATTTTT!

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  • Regular Member

I have read so many conflicting things on this. I was under the impression that part of their digestive tract is considered to be a very small stomach because it serves the function of chemically breaking down food (after the pharyngeal teeth mechanically break it down)... I would love to understand their digestive system better, but everything I read conflicts!

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  • Regular Member

Tithra, I don't think what you said is inconsistent. Goldfish don't have stomachs, but still have to digest their food, and that function is performed by part of the intestinal tract, as you said.

Tunghoi Aquarium actually has a very good description of the goldfish digestive system. Here it is:

Foods are transformed into nutrition of fish body through digestion and absorption. The indigestive food is released in the form of faeces. Goldfish is always seen with a long line of faeces because its sphincter on anus is undeveloped. Goldfish's digestive system consists of mouth, pharynx and larynx, pharyngeal teeth, intestine, gallbladder, liver, pancreas and anus. It cannot swallow big-sized meat owning to its following features that its mouth is small; jaw has no teeth; mouth protrudes forward and internal wall is smooth. The thick muscles on upper lip, which can flex freely, help some food in mouth go further and release some out of mouth; so take-in-and-send-out movements come up while goldfish's eating. Behind mouth is pharynx and larynx, under which exists a pharyngeal tooth that will grind the food. After going through the abovementioned organs, food comes to esophagus and intestinal duct. Intestine is divided into three parts: foregut mid-gut and hindgut. There is no stomach in body cavity. Goldfish's overfeeding will make foregut expanded; its front abdomen looks swollen, which is harmful to goldfish's health. It is suggested that goldfish not get too much at a time. Please feed goldfish in the way of less amount and frequent meal.

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  • Regular Member

wow alex, very informative. this is why it is best to feed them often. From what i understand food passes through fairly quickly

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  • Regular Member

Hi y'all, back after :hi a somewhat long absence, anyroad, this topic was / is a perfect way to start things off.

Both my Wakin are doing fine along with the new tank and filtration system.

It sure feels nice to be on this forum again :carrot:

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  • Admin

Welcome Back.

Yeah goldfish are an interesting fish if you think about it. :thumb:

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  • Regular Member

wow alex, very informative. this is why it is best to feed them often. From what i understand food passes through fairly quickly

Exactly, that is why they will benefit much more from more frequent small feeding than one large feeding, even if it is the same amount of food.

Like 12 pellets once a day provides less nutrition than three times 4 pellets. Just to keep it simple.

From what I read, that way the fish will also produce less waste than when being fed one big meal :)

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  • Regular Member

Very informative thread :) I love learning new stuff here :) now if I can only remember it ;) lol

I know, right? Sometimes my brain feels like a pasta strainer!

Edited by Oerba Yun Fang
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  • Regular Member

OK, doesn't anyone know why goldfish don't have stomachs?. It must have had an advantage where they originated.

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  • Regular Member

OK, doesn't anyone know why goldfish don't have stomachs?. It must have had an advantage where they originated.

I would argue that it's no so much that there is some sort of evolutionary advantage to not having a stomach. Rather, I would contend that carps must live in regions where there are plenty of nutrient rich foods, so they actually don't need stomachs because they can afford not to digest every little bit of what they eat before passing it out as poop. On the other hand, take cows for example. They've evolved to have a pretty sophisticated stomach (so to speak) because they eat very nutrient poor foods and their stomachs allow them to efficiently squeeze out all nutrients possible.

Basically, what I am saying is that goldfish are basically low efficiency digesters, probably because they live in regions where there is an abundance of nutrient rich foods.

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  • Regular Member

To elaborate on Alex's excellent point, biological structures and processes that are not useful to the species tend to disappear. Building and maintaining an unnecessary organ or biochemical pathway uses materials and energy that are then not available for more useful structures/processes. So if a stomach was not useful to distant goldfish ancestors, a mutant with a reduced stomach could use the materials and energy saved for useful things, gaining a slight advantage over those with a big useless stomach.

The lifestyle of the wild goldfish that made a stomach of little value is that of eating little bits of food continuously. A stomach is useful for digesting big meals. So people who get their stomachs stapled don't have room for big meals and lose weight. But consider the pet goldfish. This guy gets a whole day's worth of food in one or two feedings. He could make good use of a stomach. That leads one to wonder how domestication affects natural selection pressures.

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  • Regular Member

This is why I like to feed my goldfish small frequent meals per day, so that it's easier on their digestive system (since it can't hold and digest too much food at once).

But I agree - goldfish are indeed interesting fish. That's partly why I've fallen in love with them!

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the don't have stomachs to hold thier food so they have to be feed small amounts often . this is also why they produce a lot of waste :exactly

Edited by Gccourtney
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