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)
“I know that fish diseases can be so, so many things. Is anyone able to identify what’s wrong with my CPD? It started acting weird a few days ago- I’ve had this specific one for about a year and a half maybe. It’s just acting…”
“I know the video is low quality and the tank doesn't look clean but I assure you I clean it. She's just in a spot I can't get well. She likes to "sleep" there idk why. Robin has been displaying this weird zombie-like behavior for 2 days at least and I don't know what to do. I've done a 20 percent water change like 3 days ago everything is treated the water parameters are fine (I don't have testers so I took water to my LFS who is an hour away.) The only thing I”
“One of my ember tetras is acting very strange. He looks like he's shivering, and was floating in place at the bottom of my tank until I disturbed him by trying to target feed. He also seems more opaque than the others. I didn't notice this behavior yesterday. He is staying away from the school submitted by /u/Myskullisflaminghair [link] [comments]”
“My poor twig catfish(Benson) has been like this for a few days now. I asked a catfish specific group and got no answers other than "feed peas" I did give some peas (I did take the shell/skin off) and i didn't see Benson eat any, hes still grazing on the wood and glass and moving around some. Im so worried and not sure what to do! Hes my favorite fish:( submitted by /u/frostbite_owo [link] [comments]”
“He is sitting in the bottom corner of the tank gulping rapidly. Ammonia is 0, nitrite 0, nitrate under 20ppm, temp 79.5 degrees. My only thought is perhaps he ate a piece of eggshell that the wife dropped in for the ramhorn snail, and has it stuck. Any thoughts or questions welcome. Doing a half water change right now in case oxygen is an issue. submitted by /u/Ok_Blueberry_6736 [link] [comments]”
“I have 8 of them but this guy was laying on his side and the side pointed towards the sky was red by the gills but my water parameters are good and they eat daily, in my last post I listed what I think caused this but I need more help submitted by /u/AnnualLimit170 [link] [comments]”
“Bought this fish 4 days ago. Noticed this today and placed into hospital tank (left rest of the ones i bought in quarntine tank). Any idea what this is? submitted by /u/charlesamerrill [link] [comments]”
“One of my glowlights has recently gotten this wound/lesion/injury. Wanted community advice on if this is a disease and I should separate it, or if it’s just a tumor that isn’t contagious. Behavior is otherwise normal: stays in their school, eats, swims away from me. Apologies for pic quality… tetras don’t seem to like being photographed submitted by /u/Natural-Hat-3700 [link] [comments]”
“Hello fellow freshwater enthusiasts! I have been battling a bacteria infection in this tank for WEEKS.. water parameters are good. My tetras have been dying suddenly one by one, my mollies and baby angelfish keep going nose up, and baby blue electric acara has cloudy eye and lethargic… Please don’t judge. I have the mollies (except one) and the angelfish in hospital tanks that are being treated with klanaplex. All bottom dwellers are doing fantastic/thriving. What do I do?! I’ve done a few water”
“Yellow Glo Skirt Tetra - Unsure what the red is from. Does it look like trauma to you? Like it got hit with something, kind of like a bruise? Orange Glo Skirt Tetra - I noticed bumps near the base of his tail. Is that just aging and poor gene quality? Will either of these ailments spread to my other fish, or are these individual cases? Also, my glo Skirt Tetras often seem bloated as they eat up all the food before any of my other fish get there. Because of this I only feed the tank once a day. I”
“I feel depressed and I have another one I don’t want it to die too The father is clean They are well fed Since I found The body I guess its not other fishes fault? So why I lost my babyyy submitted by /u/Arshiorange [link] [comments]”
“I recently added this female guppy with 3 others, 2 remain now but one of them has a bent spine and seems very stressed. Any suggestions? submitted by /u/DifferentFuel3082 [link] [comments]”
“Any idea what this is some fish have it on mouth gills tails body I’ve lost around 20fish now I’ve tried treating with NTlabs anti bacteria but no luck any help is appreciated TIA submitted by /u/Spotted-Corydora [link] [comments]”
“I know I have posted quite a bit on this subreddit lately. Please forgive me. I recently bought some fish from a pet store. I did research on guppies prior to purchasing what I thought were guppies, along with an oto, a cory, and some cherry shrimp which i did personal research on afterwards. I was told by the woman at the pet store confidently that otos and cories do not need tankmates of the same species. (They do.) I was told by the woman that the five fish I purchased were guppies. (They see”
“Looking at the topmost neon. A quick google about a bent spine like this says potentially Neon Tetra Disease, thought I would come to the experts. They have all looked normal until about a week or two ago, when I noticed a slight curve in this one. Should quarantine him? Any help is appreciated greatly. 10gal, 1 rosy barb, 3 rummynose tetras, 4 neon tetras. Nitrite 0, nitrate 16ppm submitted by /u/Picklefan92 [link] [comments]”
“I have a Terra that is swimming around uncontrollably and I think it may be swim bladder. I’m not sure how to help or if it’s too late to do something. My tank is bare right now because I’m getting rid of all the fake things and took out anything that would hurt it. I planned to redo the tank next week with only real plants and a new substrate. What can I do to help my fish ASAP? submitted by /u/ChronicPainInTheA [link] [comments]”
“Hi all, I performed a water change like normal and noticed one of my tetras had a red line coming out the bottom of it, does anyone know what this is and how to treat it? I’ve got 6 other neons in there and a betta so just want to know if this one should be separated asap. It’s a 36L tank, been running for a year with a filter and heater. I’ve dosed broad spectrum but if anyone knows the specifics of what this could be that would be amazing 🫶 submitted by /u/Melofu [link] [com”
“It’s like a skin eating bacteria. But I’m not sure. First, 1/6 of the fish will start to loose its color. It started with a long uniform swelling across his body. Then on that swelling, the scales will be lifted, but only at that area. (Other places are fine) Then it will consume his entire body day by day as it spreads. submitted by /u/Puzzleheaded_Pea_308 [link] [comments]”
“I have a betta tank and recently put a red bristle nose pleco with my betta. At the store they all looked fine I noticed in a different tank with neon tetras that they had ick but I thought since the bristle noses were in a different tank and all looked good that maybe the tanks used different water sources if that makes sense. Anyways, now my betta has ick and I’ve been using ick-X for three days now with 1/3 water changes before every dosage and I removed the filter media because it has charco”
“My tiger endler is hanging out at the surface. He's listless only ate a little when I dropped the brine shrimp in front of him. Previously he acted like this a month or two ago with clamped fins. I treated with Fritz Expel-P and he was back to normal. The parameters are the same as is the temperature. submitted by /u/pangogirl98 [link] [comments]”
“This is my 3 year old Pirranah.. I think he's sick..he's been swimming erratic the last month now he's at bottom of tank and some film on him..our pleco is dead too. I'm doing half water change .I feed them brine shrimp and bloodworms..do I quarantine him? My 3 others ? submitted by /u/amyjane777 [link] [comments]”
“Hey friends, I've been a betta owner for less than a year and Crêpe is my third betta after losing the first two suddenly and unexpectedly (they're all PetCo buys so my partner and I think the first two had genetic issues). After the last betta died, I kept the tank up with just Cow, my nerite snail, for a few months until I was ready to do another fish. Then I got Crêpe and have been so happy cause she is my pride and joy and my world. So a few months ago, there started to be slightly m”
“Someone know why my fish is laying down all day? I’ve changed the water, I did the 30% change of treated water a few hours ago But he’s still like this, what else can I do? submitted by /u/otakugaltruh [link] [comments]”
“Long white string with a red end. Move him to hospital tank! Please help! submitted by /u/Ok-Blackberry5963 [link] [comments]”
“So. I’ve got a 20 gal freshwater tank with a clown pleco, five kuhli loaches, and an assortment of corys including aeneus (1 bronze 1 albino) and delphax. There is also an old, rather sickly male betta that I think may be female just based on how docile and timid he is. It has always been a peaceful tank with no issues. Just recently I wanted to add to the pack, as I only have two aeneus and think they need a larger group. I got three albino aeneus corys, acclimated them for several hours, and l”
“Hi! Question! One of my guppy’s is unable to swim. When I saw him like this a few days ago my thought was ‘ah… I’m losing him’ but now he stays like this. I still feed him and he still eats. He moves around but he just can’t swim. Is there anything I can do for him or is this a lost case? He is about 6 months old, not from a proper breeding process (a friend had too much guppy’s). The other 5 males in the tank are doing fine. Hope for some advice! submitted by /u/Tuull [link] [”
“Hello, my guppies keep disappearing. I’m down to 2 when I had just bought 6 July 28th to add to my remaining 1 guppy. Here are my testing parameters. Tank is a 10 gallon. Has been set up about a year and a half. Parameters seem to be stable. Let me know if you need any additional info. I never see any bodies. They are just poof gone. submitted by /u/IllCucumber1796 [link] [comments]”
“Hey there this is my one of my 2 bristlenose pleco/catfish(?) genus is ancistrus is all I know, I just found her like that 5 minutes ago. Does anyone know these symptoms? I saw her yesterday completely healthy, last waterchange was last weekend so about 7 days ago. No other fish are showing symptoms and I am going to get to water testing and setting up a quarantine now. will update with parameters soon. Tank is 180 liters stocked with lots of plants 2 adult bristlenose plecos, 7 corrdora, lots o”
“Hello! A few days ago I noticed one of my tetras looking weird. I'm not sure what is that, and I would really appreciate any advice, because I've been looking all around the net about what that even might be, but nobody seemed to have the same problem before. This tetra is around 6 months old, it has been eating well and stayed active even with this lump under it's gill, before I separated it into this bowl, just in case it might be something contagious. It's been living in a 26”
“There are marks from the water dripping on outside of tank during water changes in the photos, they look like bubbly growths on him- eg first image. But his belly is pale and he looks dark around his head. Note: his spine/ body seems to be deformed and its been like that since I got him in April of 2026 What is going on? And how do i treat it? submitted by /u/outfrommars_ [link] [comments]”
“I have a problem, I have a rainbow fish that got really aggressive (has killed several tank mates of his own species and this may be because my parents didn’t get enough of them to begin with and that stressed him) and I’ve been given two options, kill him (I don’t want to do this) or have him live alone (not ideal but better than killing him), he’s going to live in my biology classroom in a decently sized tank, I want to hear any opinions, advice, or pointers because this has been very hard for”
“I’ve been cycling my tank for awhile and just purchased yesterday: his abdomen is swollen. Is this dropsy? submitted by /u/Maleficent_Face3640 [link] [comments]”
“My oldest sparkling gourami just passed. He had been through a house move and was the only survivor of a winter power cut that wiped the tank. He also developed a spinal issue as he matured. Three years old. The tank has two younger sparkling gourami. I would like add at least one more, if not two. I'm concerned though that they will be harassed as soon as they hit the water. I'm looking for advice on this. Tank is pictured 16 gallon long. Also contains 12 ember tetra, 7 pigmy cory and x”
“Hi everyone, I need some help diagnosing my neon tetras. I've attached a photo where you can see the damage on the tail. I have 15 of them in my 110 l tank, the rest also seem to be sick, but the one in the photo is the most deteriorated. They started showing rapid breathing about a week ago, I tried increasing oxygenation, but it didn't help. I haven't introduced any new fish for about two months. Symptoms: Missing chunks of the tail and other fins. There is a milky/white substance”
“Hi all, I think this lil guy is sick. Looking online seems like ick or epistylis but wanted some opinions from more experienced aquarists. Any advice appreciated! submitted by /u/MuffinSpectacular [link] [comments]”
“This guy just came from a LFS. Today I noticed its back half is pale and it has injuries in his lower fins. He can swim around but is not schooling with the others (got 15 more rummies). Its tank mates are cherry shrimps, harlequin rasboras, and kuhlis. Nothing big or aggressive. Is there any chance he’ll recover? submitted by /u/DynamicStochasticDNR [link] [comments]”
“This tetra has like fuzzy stuff on it, my mom tried to identify it and got medication but im sure it's the wrong thing since it wasn't meant to be contagious and now two of my Corydoras have it. What is it and how can I properly help my fish, also I know the glass is dirty I am cleaning it today I was away from home for awhile. submitted by /u/03yvx [link] [comments]”
“Anyone have an idea what this could be ? I had 2 one of them died like this and i thought it was because this one bullied him and when the other one dies 1 month ago now this one is doing the same thing, what could it be submitted by /u/Aquarium51 [link] [comments]”
“For a day now, my gourami has been lethargic. Either at the bottom of the tank or floating at the top on her side. Everytime she notices me looking, she starts swimming again. But when I leave, she stops swimming and goes on her side. This morning I’ve noticed she looks like she has dropsy. In a few hours when I get back from school, I will test the water. The problem is that my family and I will be gone all day tomorrow and won’t get back until late Saturday. So today, I will try to treat her i”
“We recently inherited my FILs fish tank since he passed. We did have to transport the tank, but we had a knowledgeable fish person help direct us on that. It's been 4 days since the transfer and 11/13 guppies are hiding in the plants near the bottom of the tank. The water temp was controlled when moving and has since stayed stable where my FIL kept it. We also kept the plants and rocks and pumps in tank water during the move. We've tested all the water levels since the move and they'”
“One of my golden gouramis recently developed fin rot on its left side and has lost one of its feelers and most of its fin as result. Should it be separated into a hospital tank and what meds should I get? The only meds I currently have are Epsom salt and anti internal bacteria (sounds like the one I should use) any help would be greatly appreciated and thank you for taking the time to look! submitted by /u/Smart_Psychology4359 [link] [comments]”
“My male clown fish is acting strange. It is acting sluggish, not accepting food, and is breathing rapidly. It is not gasping at the surface, laying on the sand bed, and it’s skin look just fine. also, the female is acting normal. Black one submitted by /u/Uber_Charlie [link] [comments]”
“Is my guppy sick? I noticed similar spots on some of my other guppies. Could they be sick too? One of my guppies died yesterday and another one two weeks ago. I didn't notice these spots on the guppies that died, but I'm wondering if their deaths could have been caused by the same thing. submitted by /u/Bulky-Reputation3256 [link] [comments]”
“Ph 7.5, amm0, nitrite0 nitrate ~60. 20 gallon tank. Never seen a fishs back end not raise up except a crew of diamond tetras at my LFS that they wouldn't sell cause they didn't understand why either. If anyone has ideas, I am 💯 all ears. White clouds are my favorite, and I don't want to see one of my crew go :/ Small edit: he hasn't passed yet, but I'm realizing he looks super emaciated compared to the rest of my crew. Idk how I missed that. I might be putting him into a hos”
“I bought 6 male guppies 2 weeks ago all from my lfs. This is the only guppy out of all of them who's tail doesn't look "perfect" and I'm not sure if its fin rot or he's getting nipped by other guppies. He's eating fine, he actually even steals food from my cories. While I do notice them chasing eachother around I dont really see them singling him out. Then again, I unfortunately dont have the time to stare at my tank all day. He hasn't lost any color and is acti”
“Ive noticed my blood red parrot chichild has been a little stressed recently but everyone else seemed fine. I did a 50% water change and cleaned their canister filter anyways. I just added 2 rescue silver dollars that I took the chance to not quarantine because they were upside down and heavily beaten up from the past tank mates/owner. Now I am seriously regretting my decision because although the silver dollar's tails are growing back and getting healthier, I found my 3 year old fish (also”
“It didn't come from the store like that but it's been like that for a while, at least a month. I can't get a good photo but it looks like there was damage to the corner of his mouth and he can't close it anymore. As long as he's eating and doing well, I don't need to worry about him right? I keep an eye on him Edit: it could also be a tumor or growth of some kind submitted by /u/longalongass [link] [comments]”
“I'm not sure if this little guy has fin rot, a bacterial infection or it's just his colour coming in. submitted by /u/Le_F1she [link] [comments]”
“Hi! One of my tetras has cloudy eyes, and I was wondering if it could be something I’m doing (second terra to have issues.) if you saw my other post, another one of these tetras were swimming like they had swim bladder, then would stop and lay then repeat. Unfortunately he passed away, and now (about a week later) another tetras has this going on. It’s possible that it’s the end of their lifespans and they’re getting sick like old people in real life do, I got them 3 years ago and I’m not sure h”
“I’m at a loss. I had 3 guppies for a couple months then added a few more a couple weeks ago. Since then, one of the new guppies died after showing fin rot but no other symptoms. I isolated him when I saw the rot and he died within 48 hours. I gave him a couple salt baths and put some methylene blue in the isolation tank. Didn’t help. Then today we found one of the established guppies dead at the bottom of the tank. He had zero symptoms and was totally fine this morning. Now one of the other new”
“My neon tetra has been swimming in circles while pointing up for almost a day now. Water parameters are normal and all my other fish are fine, so I'm really not sure what the issue is. I feel bad just letting it stay like this, is euthanising my only option? submitted by /u/Doggo7896 [link] [comments]”
“So, took a fish home from work cause its sick. Columnaris or maybe fungal. Set up a 5 gallon hospital tank with water from my 10 gallon. The 10 gallon has a sponge filter and for now only has duckweed and snails. My intention was to use the sponge filter for a bit in the hospital tank, then take it out, put the sick fish in, and turn on a bubbler. I forgot to take the filter out before putting the sick fish in and its been all day. When its over, what do I do with the filter? I qant it back in t”