You’ve probably figured out that your goldfish isn’t its normal self…

And that can be really upsetting.

As this guy noted:


But what is wrong with your fish?

Well you’ve come to the right place because I’ve put together a complete list of symptoms.

Some are common.

Some are not so common.

But they’re all here.

How to Troubleshoot a Sick Goldfish


Before you read any further:

Don’t assume that your goldfish has a disease once you find your fish’s symptom here.

Most of the time “sickness” is actually caused by poor tank conditions…

…which is why you should always test the water parameters first when you suspect a problem.

You can use a simple test kit like this one to test all of the major parameters: pH, ammonia, nitrite and nitrate.

Ammonia and nitrite should always read 0ppm. More than that, and your fish will start getting sick.

High nitrates (over 30ppm) can also cause issues as well.

Check Price

The pH should also be in the right range (not far from 7.4) or it can cause issues with the slime coat, gills and fins.

If your water tests fine, then and only then can you start assuming problems that require medications.

The key is to get to the root of the problem.

So without further ado… let’s dive right in!

Behavioral Symptoms

1. Gasping at the surface of the water (gulping air): Gasping goldfish may hang at the surface of the water, appearing to “drink” the air. They also may suddenly dart up to the surface, take a quick gulp, then continue swimming. Gasping is an indication that something is not right in the tank – usually the water quality. It may be that there is insufficient water agitation or tank space to provide enough oxygen for the goldfish to breathe, but most likely the nitrite, ammonia or ph level is out of whack. Goldfish may also gasp at the surface when damage is done to the gills by store bought medications or parasitic infestation.



2. Acting lethargic: Healthy goldfish are perky and move around most of the time – foraging around the bottom of the tank for food and exploring almost constantly. When a goldfish seems weak, sad, uninterested or droopy, it is not well. Lethargic goldfish may sit on the bottom of the tank or hang listlessly at the surface of the water. They show little concern when other goldfish start to nibble at them and generally seem depressed. If your goldfish seems lethargic or sickly, check the water. A pH crash or other irregular parameter change is probably occurring.

3. Jumping out of the tank: Sometimes incorrectly called “goldfish suicide,” goldfish jumping out of the tank is actually the goldfish’s way of trying to relieve the discomfort caused by poor water quality or parasites. Prior to jumping, many goldfish display erratic behavior by darting around frantically in the tank, scratching on objects or twitching spasmodically. In all of their wild antics, the goldfish sometimes end up on the floor. But water quality or disease may not always be the problem – sometimes the pursuit of male goldfish during breeding season results in females leaping from the tank trying to escape. If you have an aggressive goldfish that is bullying the others out of the tank, try separating the aggressive fish from the rest of the tank. If you find a goldfish that has jumped out of the tank, do not give up hope! Sometimes goldfish may revive when placed back in the water again if they did not dry out completely and it has been under an hour since they jumped. The gills of the fish may be worked open gently by your fingernails if they have been dried shut. Tile or wood flooring underneath the tank provides a more likely survival chance for a jumper, as water taken out with the fish can keep it moist longer than carpet. Do not try to put a goldfish back in the water if the fish has concave eyes, gray eyes (from death), the skin cracks, or is not intact.


4. Sitting on the bottom of the tank: Goldfish that appear to be resting on the bottom of the tank are probably not enjoying a nice rest. Healthy goldfish remain active almost all of the time, and if your fish tank does not seem to have much life in it, it’s probably time to check into things. Goldfish that sit on the bottom of the tank may lean to one side, clamp their fins, or show other signs of health issues. Goldfish bottom sitting with a red belly are usually beyond the point of recovery. Why do goldfish bottom sit? Usually the problem is water quality, but sometimes the swim bladder may be the cause and it is simply a matter of constipation. Constipated goldfish scoot along the bottom of the tank when startled, rather than muster up the strength to swim regularly as a goldfish affected by nitrite poisoning does. If the goldfish is constipated, try the frozen pea diet for a day or so until the fish regains proper swimming habits.

Read More: Goldfish Sitting at the Bottom of the Tank



5. Flashing (darting / scratching): No, a flashing goldfish isn’t blinking out beams of light. 😉 “Flashing” is when a goldfish suddenly dashes around wildly in the tank, sometimes rolling over on their side to rub on the substrate, careening into tank decorations, or hitting their faces in the corners of the tank walls. It may seem that your goldfish is having a fit. Goldfish that flash are itching themselves, much like you do when you get a mosquito bite. Their movements seem uncontrolled and erratic. They are a signal that something is wrong. Flashing is a classic symptom of ich, but your goldfish may harbor almost any other pathogen instead. Any trace of ammonia, nitrite or chlorine or a pH drop or spike can cause flashing as well.

6. Spasms / jerking: When severely irritated, goldfish jerk spasmodically. They may shake their heads suddenly from side to side, convulse their entire bodies, or flick their fins. Water quality problems are usually at the root of this symptom. Parasitic infestation can also cause major irritation.

7. Clamped fins: Any issue with water quality or nearly any parasite can cause goldfish to clamp their fins. These fish swim like they are in a straight jacket; all fins folded in closely to their body as they move. In some cases, the fins flick or twitch in an irritated manner. Clamped fins, like flashing, are a sign of discomfort. Possible causes are measurable amounts of ammonia or nitrite in the water, but clamped fins often accompany parasitic infections as well. Symptoms of ich, flukes, fish lice and velvet include clamped fins. Remember – always test the water before trying to identify a disease.


8. Rapid / labored breathing: Breathing problems are identifiable by observing the patterns of the gill movements. A goldfish breathing fast commonly are suffering from lack of oxygen. If you are keeping your goldfish in a bowl (which is a big no-no; see Common Misconceptions), there is no water agitation and insufficient water volume for a goldfish to breathe. The fish will breathe hard in an effort to maintain sufficient oxygen levels. If this is the case, please move your goldfish into a larger tank as soon as possible. Rapid breathing could also be a sign of stress, especially if it is accompanied by sitting at the bottom of the tank. Stress could be caused by being moved to a new habitat after a long ride in the car from the pet store. Breeding season sometimes heightens stress on female goldfish, which become exhausted after being chased around for hours by males. But stress is also caused by poor water conditions or disease, so always check the water quality and, if there are no problems with it, gill flukes or nearly any other parasite may be the culprit. A goldfish experiencing difficulty breathing may frequently clear its gills by “yawning” repeatedly.

9. Swimming upside down: Does your goldfish seem to have difficulty balancing itself in the water? A goldfish that is stuck upside down is usually experiencing difficulty with its swim bladder – sometimes called “swim bladder disease” – the organ in the goldfish that controls its orientation in the water. Intestinal impaction is usually the cause of goldfish flipping over. That means that meals may be too large or too frequent, or consist only of one dish (such as goldfish flakes, not the best choice for their diet requirements). Feeding dethawed frozen peas sometimes helps as a short-term fix. But buoyancy troubles are not always a symptom of swim bladder disorder, or flip-over disease as it is sometimes called. High nitrites or the presence of ammonia in the tank water can cause goldfish to have problems swimming. A fish labored with internal parasites looses its appetite, and not eating causes the fish to float or flip over.

Read More: How to Treat Goldfish Swim Bladder Disease


10. Floating on side: If your goldfish is slightly tipping to one side, it may be normal behavior – especially if it doesn’t have a dorsal fin to help it balance in the water. You might also notice that the fish looks very thin. Water with high nitrites can cause this symptom.

11. Won’t eat (spitting): Healthy goldfish consume everything edible they possibly can, leaving no remains. A fish that devours its food eagerly only to spew it back out again in a ground up cloud is showing signs of a problem. Stress can actually prohibit goldfish from swallowing their food, and this is common with fish that were just brought home from the store and need time to adjust to their new home. A gill fluke infestation or mouth rot may also cause this symptom. Additionally, goldfish with internal fluid buildup (dropsy) are unable to swallow their food at advanced stages of the condition. If a goldfish becomes too sick even to eat, euthanasia is the most humane thing to do for the fish as starvation only would aid a slow death.

Physical Symptoms (By Body Part)


11. Bulging eyes: If the eyes of the goldfish appear to have fluid-filled sacks surrounding one or both of them or protrude unnaturally, Pop-eye is probably the culprit (symptom of a bacterial infection). If the goldfish also has pine-coned scales (dropsy) along with the bulging eyes, the condition is terminal and it would be best to euthanize the fish at this point. Stunted goldfish may sport permanent bulging eyes as a result of disproportionate growth.



12. Cloudy / whitish eyes: A goldfish with this symptom has eyes that look foggy like frosted glass. The fish may show difficulty in seeing food or bump into objects. This is called Cloudy-eye and is either the result of a bacterial infection that sets on after an injury, or the result of damage to the eye through some sort of burn; either from ammonia or the strong chemicals contained in some store bought medications.

13. Missing or damaged eyes: A goldfish will sometimes incur damage to the eye due to mishandling, running into a sharp tank decoration, injury from another fish in the tank, infection or chemical burns from water toxicity. In some cases, the eye may completely come off and leave the fish blind on that side. Telescope eye goldfish varieties are prone to eye loss or damage because of how far their eye stems protrude and their size. Fortunately, most goldfish are able to heal on their own afterwards and can still live a happy life. With this in mind, it is important to choose tank decorations that are fish friendly and maintain good water conditions.



14. Red gills: Though goldfish owners sometimes become concerned when they notice the red color inside a their pet’s gills, this is not usually cause for concern. It is easier to see the red color inside of the gill covers especially on white or matte goldfish. If the gills are swollen or stuck open, however, gill flukes or a bacterial gill infection may be to blame. Gill flukes, like nearly every parasite, are treatable with salt.

15. Pale gills: As previously noted, healthy goldfish gills should be a vibrant red. Pale or whitish gills are a sign of illness. Parasitic infections such as gill flukes may cause microscopic bleeding of the gills, leading to a loss of color.

16. Holes in gill covers: This is a sign of a severe bacterial infection, which might benefit from antibiotic injections. But even after treatment the holes won’t close.


17. Mouth stuck open: Sometimes a goldfish will get a piece of gravel lodged in its mouth while foraging for food at the bottom of the tank. The goldfish is usually able to work the gravel out on its own within a day, but during that time it will swim around with their mouth in the “out” position and look rather strange. It is recommended to extract the gravel for your goldfish if 24 hours has passed with no improvement. Hold the goldfish gently in one hand with tweezers in the other. Press down underneath the chin slightly, then use the tweezers to remove the piece of gravel very delicately. In some situations, the goldfish’s mouth may be stuck open without any gravel in it. The mouth may snap back into place on its own, then return to the stuck position the next time the fish opens its mouth. This is a more rare phenomenon, but it has been traced to stunting and disproportionate growth from being kept in too small of a tank for too long. The fish cannot eat and will face death through starvation unless humanely euthanized beforehand.



18. Mouth opening to one side only: This is actually not a symptom of a disease or problem with the water in the tank, but is actually a genetic defect that results in a small mouth sometimes angled to one side or even inverted. Goldfish with this condition may need to have their food served in smaller pieces than the other fish in the tank.

19. Red mouth: When the mouth shows redness and inflammation or even begins to cave in on itself, the goldfish is affected by mouth rot. The fish may rub its mouth on tank walls or decoration, causing further irritation. Blisters may also form. Mouth rot in goldfish can get very nasty very fast, so it requires immediate attention.


20. Black spots / smudges: Either natural pigmentation changes may cause a goldfish to develop black on the scales, head or fins, or healing from a recent injury. As goldfish age, their color changes in sometimes unexpected ways. There is only cause for concern if the black marks come and go in a cycle, signalling a reoccurring problem with the tank water or a bullying companion. Ammonia burns after a spike will heal black, but usually revert to the original color of the fish with time if water conditions remain relatively stable. Fins healing after a case of fin rot sometimes show black edges.

Read More: Is Your Goldfish Turning Black?


21. White spots: If your goldfish appears to be dusted with snowflakes or grains of sand, ich is probably the culprit. The protozoan is white like a speck of lint and will multiply until both the fins and body of the goldfish are completely sprinkled. Sometimes a single speck of ich may come and go, affixing itself to the tail or the wen of a goldfish when the fish has a compromised immune system.

ich copy


22. Raised lumps: Abnormal lumps underneath the skin or attached to the scales are tumors, which may be cancerous or not. Tumors come in all shapes, sizes and colors and can get rather huge when left untreated. Tumors may manifest themselves as a white lump, pink lump, brown lump or dark lump. These masses may even show up on fins as a result of toxins building up in the water. Tumors are removable, but if they are left untreated the fish may die.

23. Red spot(s) on body: These are usually ulcers, or the beginnings of them. Ulcers start out as a tiny red patch of blood on the skin, then progress until the skin begins swelling and eroding. However, red spots on the body may be bites from a parasitic infection such as anchor worm or fish lice, so examine the fish closely.

24. White, milky film on body: This is actually hyperactivity of the goldfish slime coat, producing excess mucus in response to the threat of parasites or poor environmental conditions. Check the pH for a fluctuation and test the water for the presence of ammonia or nitrite. If the water is fine, parasitic attack is probably the cause. Skin flukes, anchor worm and cause goldfish to produce a milky coating on the skin.

25. Pale color: When a goldfish has lost its color, is usually a signal that the fish is not well and is suffering from either poor water quality or disease. If nitrites are detectable in the water using a water test kit, you have probably found the cause of color loss and should take action to reduce them. Change 50% of the water immediately if ammonia or nitrite levels show up, or if the pH has suddenly shifted. Stress can also cause a lack of bright color in goldfish for a period of time until they adjust or the cause of the stress is removed, such as an aggressive tank mate. Goldfish may change their color from vibrant to dull while their immune system is battling disease, such as a parasitic attack. Any number of parasites can cause color vibrancy to go away. To ensure that your goldfish show the most coloring, provide a high quality diet, which helps to enhance coloring. Also ensure that the tank gets enough light during the day hours (but not too much – you don’t want an algae explosion!). This will help to maintain good coloring in goldfish.

26. Sores: Red, painful-looking and sometimes large sores on the body of a goldfish are ulcers. Ulcers are caused by bacteria that attack the skin when the fish’s immune system is suppressed, usually by poor water quality. Ulcers continue to eat away at the skin of the goldfish until the fish can take no more and finally dies.


27. Fluffy Patches: This may be a sign of a fungal or bacterial infection causing cotton-like growths. Patches of fuzz on the head, body or even fins might be tricky to identify unless you have a microscope.

28. Worms sticking out of body: These are anchor worms – a parasite that attacks goldfish during certain times of the year. Anchor worms are treatable if caught soon enough.


29. Red belly: A goldfish with a red belly is almost always suffering from nitrite poisoning. The effects of poor water quality, at advanced stages, can cause internal bleeding and death. Goldfish that display a red belly are at an advanced stage of poisoning and postponement of euthanasia only prolongs their slow death. Immediately change the water to save any other fish in the tank.

30. Swollen belly (bulging abdomen): If the scales of the goldfish are not raised but the abdomen of the goldfish is bulging unnaturally, egg impaction is the likely cause. A female goldfish with impacted eggs is more and more susceptible to bacterial infection with time. The only way to save the fish at this stage would be to use a hand-spawning-like method to release the eggs. Male goldfish or females that are not mature enough to bear eggs may have a kidney or liver disorder, only fixable through surgery. But remember that an overfed goldfish’s stomach will also distend beyond its normal size, which is why overfeeding is never a good idea.



31. Sunken belly (abnormally thin / wasting away): A goldfish with a sunken belly is usually experiencing the harmful effects of ammonia accumulation in the tank. This can cause the fish to be susceptible to bacterial infection, which makes the stomach appear concave. If the water is fine, an attack of goldfish flukes or another parasite may be causing the goldfish to lose its valuable nutrients. A sunken belly may also be a sign of an underfed goldfish.

32. Bent / kinked back: This is scoliosis in fish, a condition caused by either genetics or electrocution. Scoliosis may cause the scales to pinecone at the curve of the spine. Scoliosis has no cure in fish.


33. Scales sticking out all over (pineconing): This is dropsy, a condition where the buildup of fluids in the goldfish causes the body to swell in such a way as to make the scales stand out and prickle. Dropsy itself is not a disease; it is an indication that something is wrong with the water quality or with the internal organs of the fish. Dropsy, when combined with bulging eyes, is terminal.


34. Scales peeling: When the scales of the goldfish in an area or a patch seem to have peeled back, leaving a bare place on the goldfish’s body, that is a burn. Burns from fluctuating pH levels may occur at any time while the tank is still cycling and trying to establish a colony of beneficial bacteria.

35. Scales coming off / missing: When a goldfish has missing scales, there is a distinct area on the body of a metallic scaled goldfish that reflects no light and can appear darker than the rest of the scales. A goldfish can lose anywhere from one scale to many, depending on the severity of the problem. Goldfish that have many missing scales are actually showing a symptom of a symptom; the scales are being knocked off the goldfish as a result of flashing. If the problem gets resolved (either fixing the water quality or eliminating the presence of parasites), the scales should grow back with time. If the goldfish is a Pearlscale, however, the missing scales will not resemble pearls but regular scales when they grow back. Please note that a goldfish may also lose a scale or two when trying to squeeze through the opening of a decoration in the tank that is too small to fit through.

Tail & Fins

36. Bloody streaks / red spots in tail or fins: This is a sure sign of a serious problem with the water. High ammonia or nitrites can cause blood hemorrhaging (broken blood vessels) of the veins in the tail of the goldfish, resulting in thin red lines or spots of blood appearing in the fins. Water changes and proper room in the tank can help ensure recovery.


37. Shredded or frayed tail or fins: Traceable ammonia or nitrite levels in the tank can cause the fins of a goldfish to shred and fray like someone has snipped the goldfish’s fins over and over with a pair of scissors until the ribs of the fins give the fish a spiky appearance. Fin rot, too, will cause the fins to fray and disintegrate. The parasite Hexamita, a protozoan brought on by poor environmental conditions, can cause this condition also.

38. Tears / splits in tail or fins: If there are multiple goldfish in the tank, sometimes aggression may occur and leave the victimized fish with splits in the fins. The bully may grab a goldfish’s tail in his mouth and tear savagely, causing rips to ensue. Additionally, poor water quality may cause splits to appear in the tail. Frayed fins may be a sign of fin rot.


39. Milky film on tail or fins: This is caused by excess mucus production in response to poor environmental conditions or parasitic attack. Milky skin is easily detected on varieties such as the Black Moor goldfish.


40. Floating poop / air bubbles in poop: The diet of the goldfish is not varied enough, and air bubbles from meals upon meals of dry flakes are accumulating in the fish’s digestive track and expelled in the casts. Healthy goldfish stool should be the color of the goldfish’s food, usually dark brown in color, and sink to the bottom.

41. Long, trailing white poop: Hollow, stringy poop is the outer casing of the stool. They are called casts, and are normal in goldfish that are kept with sand as the substrate. However, if the poop is long and trailing, this indicates an internal issue such as intestinal bacterial infection or a poor diet. (Sorry for the following picture…)


“How Can I Use This Information For My Fish?”

So now you know what your goldfish’s symptom is from.

What should you do?

Lucky for you, we created just the thing to help you nurse your goldfish back to health and keep it from falling sick again.

You’ll also learn the 5 critical mistakes most people make in your situation – and how to get things back on track fast.

It’s all in our eBook called “The Truth About Goldfish.”

Join the Fastest Growing Goldfish Facebook Group to Post Your Question

I’ve got to say I was blown away by the number of comments this article has gotten.

Since so many people need help, I decided to start a free private goldfish Facebook group as my way to say thanks to my awesome readers.

It’s a great place for people who are struggling with sick fish to get advice from fellow hobbyists and post photos (something the comments section on here can’t do).

There are so many great members willing to dedicate their time to helping others…


So, what are you waiting for?

Head over to the group now. I look forward to seeing you there! 🙂