You come home from your day to do your routine feeding and check-in on your fish. To your surprise, you notice that one of your fish is exhibiting strange behavior and is acting lethargic. After a closer look, you see that something is hanging off your fish. What could this be?
After seeing regular poop hanging from your fish in the past, you know that what you’re looking at now isn’t just a normal poop.
Noticing the red color and stringiness of the hanging object, you’re able to determine that this is your fish’s intestines hanging out—this is commonly known as vent prolapse.
While this is scary and may leave you with many questions, it’s not out of the ordinary for marine life enthusiasts, and there are reasons/ solutions around this problem. Keep reading to learn what causes your fish’s intestines to hang out and how it can be treated.
Three Signs Your Fish is Facing Vent Prolapse
Before deciding what to do about this issue in your fish’s case, it’s essential to identify the problem correctly; once you’re specific and know for sure what is going on with your fish, you can begin to take action and make a treatment plan.
Let’s break down the visible signs that might mean your fish is facing vent prolapse.
A Mass is Protruding from the Vent of the Fish

This will be the most obvious sign that your fish is dealing with vent prolapse. It’s important to distinguish this protruding mass from regular poop hanging out of your fish.
A normal poop will have a lighter color and eventually fall off on its own. Vent prolapse will appear darker, usually red, and have a stringy consistency.
Additionally, this won’t just fall off by itself; some sort of intervention will be necessary for this hanging mass to be released from the fish.
Your Fish Seems Depressed
With strange, erratic swimming patterns, you might notice that your fish’s behavior has changed. Zig zagging rapidly back and forth throughout the tank are sure signs of unusual swimming patterns.
In addition to strange swimming patterns, you might notice that your fish seems frantic. You’ll know this to be true if you see your fish acting strangely towards other fish in the tank or jumpy and uneasy around your water filter.
Another sign that your fish faces depression is if it spends most of its time laying at the bottom of the tank with its fins locked by its side.
This sign of tiredness and low energy, combined with frantic swimming patterns within the same time frame, are typical types of behavior for fish that are depressed.
You Notice Anorexic Behavior
The most common sign that your fish is anorexic is if it refuses to eat—especially if it hasn’t had any eating problems in the past.
This is something that should be addressed as soon as you notice it. When your fish refuse to eat, the clock starts ticking—this can be deadly if not handled quickly.
A less obvious sign that your fish is anorexic is if you notice a loss of buoyancy control. The fish won’t have the proper nutrients to control its balance and will likely sink lower into the tank.
Lastly, if you see your fish are spitting out the food that you’re dropping in the tank, it isn’t because they don’t like the flavor of the food. This is because there’s something bigger going on, likely a prolapsed vent, that’s causing your fish to spit out its food repeatedly.
Be sure to pay attention to any of these occurrences in your fish. If you’ve determined that a vent prolapse is causing these symptoms in your fish, you need to act quickly.
Causes of Protruding Intestines
A few reasons why your fish’s intestines have started to protrude. Sometimes it’s within our control as marine life enthusiasts; sometimes, it’s from events you won’t have control over.
Overfeeding of Your Fish
This is within your control as a fish owner. If you’ve been doing this, don’t feel bad about yourself—this is the most common mistake that new and veteran fish owners will make.
As fish are very opportunistic, they will typically eat whenever food is available, so it’s easy to slip into a pattern of accidentally overfeeding them.
Depending on the kind of fish in your aquarium, it’s typically fine to feed them just once a day. If you’re feeding your fish two to three times a day, you’re most likely overfeeding them, which can lead to vent prolapse.

Switching your fish’s food to something more manageable to portion out for you as an owner is a simple solution to solve the overfeeding issue.
You can also try to switch up your fish’s feeding schedule; if you currently feed your fish at night, try feeding them in the morning; take notice of any differences in how your fish are consuming their food once you’ve adjusted the schedule.
Possible Infection in Your Fish
There are many reasons why your fish may have contracted an infection and is now facing a prolapsed vent. If you think your fish has an infection, the best thing you can do here is consulting with a vet.
You can try treatments at your homes such as levamisole, metronidazole, and praziquantel. Try introducing these chemicals in your tank to see if it helps with your fish’s possible infection.
Your Fish Has Straining from Passing Eggs
The number one cause of straining your fish from passing eggs is if your fish’s environment isn’t suitable for reproducing.
Poor water quality, the male to female ratio is off, the tank is overcrowded, or your fish isn’t receiving enough nutrients can all cause this.
If you’ve noticed your fish’s intestines hanging out and think that it might be suffering from straining due to passing eggs, you can try to increase the water temperature in your tank or introduce Epsom salt into the tank. (more on this later)
Doing this will make a better reproduction environment, and your fish will have an easier time passing eggs.
This Isn’t a Normal Poop
Fish constipation is prevalent and can appear similar to vent prolapse. Many marine enthusiasts make a mistake in mistaking fish intestines for fish poop. If it’s just poop, it’s generally harmless and will pass on its own—if it’s vent prolapse, it needs to be addressed quickly.
If you’re feeding your fish on a flake or pellet diet, it will likely cause constipation in your fish and cause the poop to hang from your fish. If you don’t feed your fish with these kinds of food, your fish likely has vent prolapse.

While poop and intensities look slightly different, the best way to distinguish this issue is to pay attention to the scales on your fish. If your fish’s scales are sticking out from its body, making your fish look like a pinecone, then this is a sure sign that your fish has vent prolapse and not constipation.
How to Treat Vent Prolapse in Your Fish
While vent prolapse in your fish can be frightening, there are ways for you to treat this. Relax, don’t panic, and get your fish back to good health.
Surgical resection
You’ll have to administer anesthesia to your fish before doing this. Using an encircling ligature or Co2 laser, you can cut and remove the hanging prolapsed vent from your fish.
You can also insert a syringe into the genital pore of your fish’s abdomen. Doing this will cause the hanging intestines to be released or sucked back into your fish’s body.
Conservative Treatment Options
If conducting at-home fish surgery freaks you out, other options are to treat your fish’s prolapsed vent conservatively.
The first thing you can do is monitor your fish closely and see if the prolapsed vent goes away on its own. While this isn’t the most common scenario, it is possible.
Another solution is to apply sugar granules on the fish’s hanging intestines. Sugar can reduce swelling and cause the prolapse to go back inside your fish.
Lastly, you can try to massage the prolapse back into the fish. This may be a little difficult as your fish is swimming around, so you’ll need to use some sort of fish relaxing agent.
Massaging the hanging intestines can reduce inflammation and encourage the intestines to go back inside of your fish.
Use Epsom Salt
This is the most likely way to treat vent prolapse in your fish. If you have multiple fish in your aquarium, you’ll need to isolate the fish with hanging intestines to a separate tank.
In rounds, add 1/8 of a teaspoon of Epsom salt for every five gallons of water in your tank. Once you’ve done this, increase the water temperature to 78°-80° Fahrenheit.
Your fish will need to remain in this environment for at least a couple of hours. The Epsom salt and increased temperature will relax the swelling and hanging of the guts, causing them to go back inside of your fish eventually.