Fish Sickness Is Hard to Diagnose at Home
Several posts express concern about fish health problems, including white spots, tail rot, swim bladder issues, and general sickness. Users are seeking advice on treatment, isolation, and potential causes like stress or disease transmission.
SOURCES (60)
“All other fish are doing fine. The tetra is breathing and I’m planning on changing out water. I found it stuck to the tank filter. It’s been trying to swim. submitted by /u/BIGGUYISM [link] [comments]”
“Is there something wrong here? Swims fine,eats well. 10 gal. 5 coreys and 3 neon tetras + 1 other guppy.No water quality problems. Regular 25-30% water changes. Help appreciated. Thnx submitted by /u/Relative-Math3351 [link] [comments]”
“I believe my tank is infected with fish tuberculosis. My parameters are all normal, i do a 20% water change every week. i have a 20 gal high with ember tetras, cordydoras, shrimp, and a recently deceased honey gourami. I noticed that slowly i started losing fish. some were getting very skinny and lethargic, refusing to eat and then just dying. Some had weird scales/skin and a curved spine. I’ve decided to close the tank and add no new fish. focus on water parameters and comfort, and removing dea”
“my guppy both are sick and the left one just passed away ytd ( he seem to not eating and bump into thing in the tank ) so i move them both to hospital tank with 3L water and 3g of salt. Currently there only one guppy left he seem to have that behavior as well not eating and bump, what illness might he have ? what should i do now? submitted by /u/Amazing_Shake [link] [comments]”
“I have had these phantom tetras for almost 2 years now and they have always had these black spots on them , I tried looking it up but no luck , I have other fish in the tank and they don’t have these black spots , I’m really curious any feedback is greatly appreciated submitted by /u/Ok_Entrepreneur_8565 [link] [comments]”
“Fish-in cycle, 3 weeks in, 29 gallon tank, 5 zebrafish and three baby bristlenose plecos. Noticed on Sunday what looked like a white patch on one male zebra danio. Looked a bit bigger yesterday (looks about the same today). Unfortunately he moves constantly so it’s hard to get a good photo. I went to our LFS and they said not to treat the fish because it’s a cycle fish. They feel sure it’s not ick (I agree it doesn’t look like ick). I was kind of appalled as I suggested I could try to get the fi”
“(Not my tank or fish) Saw this fish and was wondering what the black colored growth or maybe parasite is under the jaw/mouth area. If anyone has some clues to what it could be and treatment ideas that would be appreciated. This was sent to me so I’m not sure if they want to treat but just in case i would like to relay treatment advice to them. submitted by /u/AdWrong7803 [link] [comments]”
“TRIGGER WARNING - *Scrape Injury* I need help with my Betta. I have a heated, filtered, and planted tank. My readings have always been 0ppm of Ammonia, Nitrite, and Nitrate. PH is 7.8, Kh is 10. (I've had to start dosing small amounts of nitrogen for the plants.) So this isn't a water quality issue. I got her May 22nd, 2026 and I acclimated her slowly like I normally do with new fish. She's a blue marble female plakat halfmoon. When I got her she seemed bored and lazy in the store ta”
“I just started a 10 gal fresh water aquarium- i have a hand full of shrimp 4 pygmy, 4 guppies and 4 endlers and who knows how many snails. My aquarium is heavily planted has wood, some tannins no fake plants. I use a liquid test kit and every test is coming up fine I have found copepods and all my shrimp seam fine. I keep finding dead fish, two guppies an endler and a pygmy all dead, and not eaten or anything. I’m really confused on how they are dying, they are fed every other day with plenty of”
“Just thought some people would think this is interesting! A couple months ago I had some disease break out in my tank, and it killed off every single one of my guppies. I had bagged my last two remaining girls to separate them from my main tank, and they expelled these fry prematurely before promptly kicking the bucket. I was not expecting these guys to live, at all. Their yolks were very exposed. For the first week or so, they couldn't even move, they laid slumped over on their sides or ups”
“Other 4 guppies are doing just fine, everything within proper parameters. He will move if I stir him with the net . I have only had them for like 2 months, is it possible he was already old when I bought him? Edit: he’s back swimming around with his brothers I have no idea what’s going on Another edit: all my dwarf corys are missing too, something fishy is going on (😎) submitted by /u/Ihopeheseesme [link] [comments]”
“Hi there, I have this unfortunately unhealthy looking cloud mountain, they have been fine but the last day pr two seem to have lost a lot of their colour, and have been swimming at the top of the tank, all the other fish in the tank (5 other cloud mountains and 3 Dannios) are all fine, eating swimming and have good colour. My tank parameters are fine 0 nitrate nitrite was a bit high but going to add bio boost to help that, and ammonia was 0 too, all other parameters were in range of what the fis”
“My mother has a couple fishes, and one fish seems pregnant for months now, and this one has this line coming out. I might be worried this could be a parasite instead or a dumb long as fuck poop line. I love all animals so this concerns me. submitted by /u/Late-Account-6260 [link] [comments]”
“For context i just deep cleaned my tank today. Its been turning white for a bit but a few days ago i noticed the orange around the gills. Now today i see it looks like its shedding or something. Can someone let me know whats going on? submitted by /u/GoAway127 [link] [comments]”
“20 gallon tank, some gourami, flying foxes, and tetras, as well as 3 of these black spotted guppies. and We just got back from vacation and noticed this. Is this other fish nibbling? Is it infected? Why is it red-orange? Just looking for some advice about the tail. Thank you so much in advance. submitted by /u/aptadnauseum [link] [comments]”
“I saw a couple of dark red spots near gills and dfins of my goldfish with white lines attached to it. These tentacles are clearly visible in the end of video. Could this be ammonia burn, stress or physical injury ? How to confirm and what to do? Pls help submitted by /u/Head_Spring8522 [link] [comments]”
“I have a 100L with 8 black tetras (breeder variety, hence the white-pinkish look and longer fins) and several other species, but that does not matter for now. I saw this fish in this spot yesterday after feeding and thought he/she looked a bit bloated, but it was around bedtime and it was still responsive to me. Come today & I’ve noticed it hasn’t moved much from this spot and doesn’t look great. Could this be dropsy? Bloat? I feed them the hikari micro pellets, they also eat my hikari sinki”
“I am a total beginner on keeping fish I begin keeping fish for about 2 weeks but my guppy keep dying for no apparently reason so I buy a test kit but I don't know what it mean I do ammonia test But i forgot to take a picture I took a look at the paper it show 0.1 or less anyone with a better knowledge please tell me I don't want to see any more of a die please criticize me is okay if you see anything wrong with it I just don't want to see it die for no apparently anymor”
“Hi everyone, My parents have the following problem: One day, all our fish died. The water was cloudy, and it looked like there was some kind of fungus in it. After that, we completely changed the water, bought new gravel and decorations, and replaced the filters. But right after that, the fungus showed up again. Does anyone know what this is? What else can I do? Im no Aquarium Expert so I Need to forward all questions to my parents for answers :) submitted by /u/Comfortable_Main6978”
“Two days now, our big male swordtail is swimming up near the top, right under the filter. He seems to be struggling to keep afloat, side fins are in full flutter. We've stopped feeding for a day now, and no other fish are affected. If he gets startled, hell dart away like normal, but then usually comes back here shortly after. Thoughts? submitted by /u/JohnnieWalkerRed [link] [comments]”
“The first 2 are now and the last one is from December. Same tank mates, plants and system, feed 1-2x a week with blood worms. Water quality is fine/normal. Any suggestions? submitted by /u/_Laxaholic_ [link] [comments]”
“I tested his water: No chlorine or ammonia Low nitrites High (100 ish) nitrates Temp is around 70f He's fluttering when i move his tank but otherwise just laying there Main question: I bought 2 gals of betta water from the pet store, can i immedoately put it in (slowly) so he has more clean water? Or do i need to acclimate him over time or something? submitted by /u/doccottlestan [link] [comments]”
“this is a 10 gallon tank that i wanted as a male guppy tank. it was set up early june and cycled for weeks. its live planted with fluval stratum on the bottom and white sand on top with some rocks scattered around. 2 pieces of spiderwood and some live moss decorations. i first got 4 guppies from usually a reliable LFS plus 2 amano shrimp, and 4 chopstick snails. if i remember correctly 1 of the guppies from this store died a couple days later. my shrimp and snails are doing amazing. so at this p”
“Since yesterday, I noticed that my fish has been twitching while swimming and the top of its head seemed to be more yellowish than others from its group. It seemed to be having trouble swimming too cuz every now and then, it’ll suddenly flop down before quickly trying to swim again. I’ve checked the ph, nitrates, ammonia of my fish tank but everything is stable. submitted by /u/Sherineeex [link] [comments]”
“Hi, I recently noticed this grey triangle thing on my betta fish It appears behind his gills and in front of his fins I'm new to this, and can't tell if he's flaring or if it's a medical issue? Please help, thank you so much submitted by /u/Serious-Zucchini2779 [link] [comments]”
“Hi all, 20 gallon tank, running for 5 years completely cycled ammonia is consistently 0, nitrite 0 nitrate usually ~10-20. For the last 2 years I have had only 4 amano shrimp in the tank. I purchased guppies online last month that got shipped to my house in 2 orders. The first order got here (2 females) around 2 weeks before the second order (2 males). I noticed one male about a week later with a fuzzy growth on him. I have had saprolegnia before so i dosed with nox ich but he passed. About 2 da”
“Hi, Hoping to receive some help. I've had a 40 gallon tank running since April. Added around 15 neon/cardinal tetras early June. Had two die early on and then they settled. 2 weeks ago I received blueberry tetras. Had two die within a few days, they told me they can struggle with adaption as I was getting them. Somewhat expected but a bummer. Since then, 3 additional neons have died. I see like 1 white spot on some of the fins, it hasn't progressed and none of the fish that died really s”
“I’m looking for some advice because I just brought home a very young Electric Blue Acara today, and immediately started having severe balance issues. Symptoms: Rolls onto its side,spins nose-down, floats to side occasionally but is now mostly lying on its side at the bottom. Has a very hard time staying upright. Ammonia: 0 ppm Nitrite: 0 ppm Nitrate: 0 ppm pH: 7.8 Temperature: 77°F The tank is a planted 75-gallon aquarium. The fish store recommended trying an Epsom salt bath, which I’m doing. Si”
“Today I noticed one of my neon tetras isolating himself from the rest of his school in the upper corner of the tank. Upon closer look, it appears he has a bump at the bottom of his body. Anyone seen this before or know what it is? I have melafix and kanaplex on hand. Note: He doesn’t live in a cup. I just put him there to quickly quarantine. submitted by /u/Difficult_Dot_3549 [link] [comments]”
“I bought a 25L tank 3 weeks ago, went back after 24hours as per the shop recommendation and bought two female bettas. One betta died within 24hours the other is the only surviving fish. I then got 5 tetra and 1 died within 24hours the rest survived a week. I’m not going to get anymore fish for the time being I plan to keep the female betta where she is doing daily water changes and tests and buy 100l tank set up tomorrow and start cycling it for a month or so then moving the betta over and event”
“Not the best picture but, what could that white mark be on this rummy nose tetra? Two of our angel fish have eggs in the tank and have been very protective of them. Could it be that or a disease? Should I keep this one separate? submitted by /u/reddituser2185 [link] [comments]”
“My guppy has these blob popping out her anus sometimes it extends and is a lil fuzzy but not like the parasite camallanus I see online what could it be please help if you can thank you in advance submitted by /u/kewldude42 [link] [comments]”
“It's a White Cloud Mountain Minnow. I just noticed this. Is there anything I can do to help it? submitted by /u/herbblurb [link] [comments]”
“He’s in a 55 gal tank with another male gourami who is the boss, no attacks no jaw locks just assertive dominance without major violence. Water is turbulent because other fish moved fast and dirtied my water. Any ideas of what it could be? submitted by /u/Aquarium51 [link] [comments]”
“I noticed one of my fish developed a strange bump under its belly. It wasn’t there before, and I’m not sure what it could be. The fish is still swimming and eating normally. submitted by /u/SwimmingSky1183 [link] [comments]”
“My blue Acara was perfectly fine yesterday and today has what looks like an eye injury and some stringy thing on the top of his tailfin (zoomed in at the end of the video). Does this seem like a parasite situation or do you think its an injury from hitting something in the tank? His other eye is fine. No other fish has any signs of parasite or injuries. Going to add in some stress guard to see if that helps. Let me know what you think. submitted by /u/James01147 [link] [comment”
“Hi guys I’ve been in the hobby for a while but not great with sick fish. From these shoddy pictures what do you think is wrong with the fish? Is this saddle back disease or something I could treat with an anti fungal like itch-x. The white spots are definitely worse than yesterday. I’ve had the fish for less than a week and none of the other fish are showing any distress or similar lesions submitted by /u/DrCack [link] [comments]”
“There are some koi keep in a pool not too far from where I work, and they seem to be having signs of sickness. I want to help them or at least bring it up to someone but I don't even know where to start. Is this a fungal or bacterial infection? I'll be honest, I'm not a fish person. submitted by /u/volpiousraccoon [link] [comments]”
“Need to vent because the logic here is blowing my mind. I picked up a Snakeskin Guppy from That Fish Place / That Pet Place on Saturday. Dead in less than 48 hours. Tested my parameters at home—everything was completely fine (0 ammo, 0 nitrite, low nitrate). I know TFP has a strict "no guarantee" policy on livestock, but since I literally just bought the fish, I figured if I brought in a water sample and proved my tank was healthy, they’d show a little leniency and basic customer goo”
“I recently got home from a trip and came back to see one of my my black phantom tetras looking FAT. I also lost some fish while I was away (someone was taking care of them) so did she eat some dead fish? What should me next steps be? submitted by /u/Ancient_Can9325 [link] [comments]”
“Is this the disease ich on my Corydora? No other corydoras nor any other fish have any signs of it. I am hoping this is just fatty tissue but it keeps spreading on him. What should I do about it? submitted by /u/Glittering_Excuse920 [link] [comments]”
“He's acting weird since I've changed the water as usual. I never saw them swimming like this submitted by /u/Blue_cactus_07 [link] [comments]”
“Ive had Gerard since Wednesday and came into the room to him leaning on the tank ornament just now, breathing quite rapidly. I managed to get him to move easily but as he swam off he was leaning a bit to the left but then steadied and swam off normally. Now he’s perched behind the wood. Could he just have been sleeping or should I be concerned? Well, I’m already concerned 😢 Water parameters all measure perfect, oxygen flow and temperature is correct. I’m unsure what to do 😢 submitted by”
“Hi you all, I have a question concerning my 8 year old Cherry Barb. Over the last few months I have seen him starting to tip forward with his head while standing still in the water and to swim up in straight line from the ground to the top of the tank in a way that none of my other Cherry Barbs do. Now over the last few weeks he started to just lay on the bottom of the tank more and more whilst still swimming on the ground and roaming around. He is also still eating and does not look sick in any”
“Hello, this spot/growth or whatever it is appeared on the tip of the tail on my tetra glofish. I'm not sure what it is, having done a search it doesn't really look like anything that comes up. Any help or advice would be appreciated. Thank you. submitted by /u/claymc52 [link] [comments]”
“I thought it was dead, but when I went to get it out, it swam away and ended up like this. I was watching it, and one of my other fish hit it. It moved to be lying on its bottom. submitted by /u/Austin22001 [link] [comments]”
“Im just worried hes stealing food from the others. Water parameters are ideal and he isnt showing any signs of struggle while swimming or lethargy. I feed them 1-2 times a day with pinches of tetramin tropical flakes and i throw frozen bloodworms and brineshrimp into the mix every now and then to give them a variety. submitted by /u/Particular-Past7881 [link] [comments]”
“I woke up to an injured or sick rainbow fish. This is my first fish injury/illness. What do I do? Tank is 2 months old. Everyone has been thriving since being put in. Ammonia is 0 Nitrites 0 Nitrates 5-10 Everyone was doing great last night before bed. Woke up to this kamaka rainbowfish looking pale with his head two different colors? One side dark and one light? Bruising? What should I do? He hovers in one spot and did not come eat with everyone else. I’ve had no problems with aggression. Tank”
“Rough go in the tank for the past couple months, just got ride of ICH, now this red thing is on my tetras gill and he not swimming very good, any idea what it is so I can try to treat it before others get sick? Ammonia 0 Nitrite 0 Nitrate 5-10pm PH 7.5-8.0 46 Gal tank Did my last water change yesterday to complete the ICH treatments Thanks submitted by /u/kennyatshop [link] [comments]”
“Hi everyone, I introduced my Black Moscow guppies to my aquarium about 24 hours ago, and they are extremely active. They spend a lot of time swimming back and forth vertically along the corners of the tank, going from the bottom to the surface repeatedly. The tank is 60 liters, planted, and has been running for about 4 weeks. I had the water tested at a fish store and they told me the parameters were good. The temperature is also within the recommended range, and the filter flow is not particula”
“Last week I welcomed some bumblebee goby’s to my collection. last night at some point the power went out and the air pump stopped working, I noticed this morning when I got up that they were finally out and jumping around/ eating etc and when I turned the pump back on I noticed almost instantly they stopped and hid again. My question is do they not enjoy the heavier water flow? Should it be turned down? or is it just a coincidence? submitted by /u/paigechantelle [link] [comment”