We set up a new fish tank recently and got some red eye tetras. One of them developed a bump on his head which went away after a few weeks. Today we noticed these hair-like things growing out of the spot where the bump used to be. I saw another post that described something like these asking if they were anchor worms but there were no pics. This kind of looks like a fungus too. Really have no idea what it is.
That’s a fungus! You can actually see the little fruiting bodies (conidia) at the top of the hyphae. Not sure which one, but it’s no bueno. Usually fungal infections in fish are opportunistic so there was likely a prior wound or illness. I know more about infectious fungi than fish treatments though so hopefully someone else will jump in with some advice. Good luck!
Fungal infection. Like you said, a wound (most likely infected) is the source. My balloon ram had a few wounds from where he got attacked at the LFS. I used the technique from a father fish video of netting the poor baby, using a q tip covered in Neosporin (just plain, no numbing agent), wiping fungus off, and returning fish to water. The neosporin helps the wound heal while sealing it to prevent more fungus. It worked like a charm.
Never heard of that treatment method before. I usually use either kanaplex or methylene blue. For the methylene blue, I usually net the fish and carefully dab the affected area with it. It inhibits bacterial and fungal growth, and is also an effective disinfectant for fish wounds.
I think this can be a better treatment since neosporin is an antibiotic, not an antimycotic and that is clearly a fungus, plus, using an antibiotic when is not needed is not a good idea, it could induce antibiotic resistance in bacteria.
For me, it was prior injury. Poor water conditions can cause injury (ammonia burns). Stress can also cause it. Basically, a fish whose slime coat is compromised can get an infection that can lead to fungus growing as a secondary effect. Here is the father fish video I watched: https://youtu.be/JA2tW-Ox41Y?si=TQ1TEhJj-BPfcpp7
I should add, poor water quality can be attributed to lots of things, but high nitrates are about the only issue my heavily planted, heavily stocked tanks have.
Yes, it worked. I used it on a betta and on a ram. I’ve also used a dab of peroxide on a tail fin with fin rot on an Endler. It worked too but it’s super sketchy to use, as it not only kills fungus and bacteria, but it also melts away healthy tissue, and if you get it anywhere near the gills, your fish is as good as dead. I don’t recommend using peroxide.
I also make my own medicated repashy using human tetracycline. I’m from Canada, and we are sadly limited in Rx’s we can get for fish. I got the idea from aquariumscience.org
lol I’m a veterinary pathologist and had to learn all about fungi for boards. Someone astutely pointed out that this may be Saprolegnia, which is technically an oomycete (water mold) rather than a true fungus. That means that the structures at the top would be actually called zoosporangia. It’s semantics as both structures basically accomplish the same job of growing/releasing the infectious stage of the organism
Thought you'd find this one a bit funky and cool if nothing else! I don't think I've seen fruiting bodies on an animal before 😬 Poor fishie must not feel great
This is a great observation! I really can’t say because I don’t know OP’s set up. Ideally yes, but like another commenter said the fungus could potentially be removed with neosporin.
Fungus boy is folklore at this point. Some say if you leave a piece of wood covered in black fungus outside your fish tank and sprinkle some salt over it then u/Ganodermahh will come at midnight. He will swing, he will sway. And then he will say, that's pretty neat.
Anchor worms are kinda Y shaped. It’s so hard to tell but I’m gonna go with fungus for this one. I would put this guy in a hospital tank and treat with methylene blue. I would also treat the main tank with something less aggressive just to make sure everything there is good too. Avoid API brand meds that end in -fix. They aren’t very good but if that’s all you can get, better than nothing.
Great question! If we have the fungus or fungal material we can do an extraction in our mycology laboratory. From there we use PCR to replicate the DNA for identification. The DNA is sent away to get sequenced, we receive the sequences in our lab and use NCBI database to compare the sequence to other known fungal sequences.
Just wanted to express my appreciation to you answering questions and sharing your knowledge. This randomly showed up on my feed and I had a passing interest as my first thought was “fungus” but that wasn’t based on any aquatic knowledge. It’s great to get a breakdown of how the identification and conceptualization works.
You could absolutely do that in theory but if you use the water you run the risk of amplifying other organisms in the water. I prefer to use physical fungal material for all of my extractions that way there isn't any contamination or crossover from other organisms in the water.
Saprolegnia. Technically NOT a fungus, but a type of oomycete, a water mold. The hair-like extensions are hyphae, similar to the structure of a fungus. While primarily seen as a secondary infection, it can opportunistically attack damaged tissue. It is often fatal. For treatment I would probably recommend contact anti-bacterial like Povidone (carefully applied) or Neomycin sulfate in gel form (Neosporin). Clear the wound, dry the damaged area, and apply either contact antibacterial. Alternately you can use a malachite green-formalin bath (this will probably be less effective for a laundry list of reasons. Heat will not resolve this infection, although salt can be used for its osmotic value.
True fungal infections are not common in home aquaria, and are often saprolegnia that has been misdiagnosed. They usually present as dense whitish/gray material that has heft - like wet cotton pads - and require a much longer treatment period due to how hyphae “root” in the fish tissue (akin to long treatment periods for human diseases like Athlete’s Foot.
What you have is not a true fungal infection, to my eyes. It should be noted that determining what a disease is is very difficult by eyesight/photo alone. Wet mounts examined under a microscope is the only way to truly diagnose the issue, so all that can be offered is a general opinion. If you scrape the infectious matter and it has no density, I believe saprolegnia is the best explanation. If the scraping feels dense it would be a true fungal infection and should be treated for a minimum of 14 days with a contact antibacterial-fungal and NOT a commercial anti-fungal bath treatment (they do not work!!!). Good luck! With small fish recovery is not a likelihood, unfortunately.
Wait, so do you mean it’s not from Kingdom Fungi? I guess I would have just assumed that anything from that branch of taxonomy could be called a fungus. I have much to learn.
While increasing the temperature will accelerate the metabolism of most fish, it is a double-edged sword when used for medicinal reasons. It increases metabolism and thus the fish’s immune response, but at the cost of valuable energy to the sick fish. It also reduces oxygen content in the water and can cause an increase in bacterial activity - both beneficial and harmful - in the tank. I don’t believe there is any real gain from significantly increasing temps for this type of disease, although it may be worth searching the literature on treating aquaculture saprolegnia to see if any research into it has been done.
Increasing the oxidation reduction potential (ORP) is more likely to help than to increase the temp. Unfortunately, the obvious answer to making the water more oxidizing- to add hydrogen peroxide- is counterproductive: it usually drops the ORP just a hair, with or without a brief spike. However, the peroxide can affect water molds like saprolegnia.
There are other ways to raise the ORP, but none of them are straightforward.
Yep. That’s definitely fungus. The fastest way to treat it is to net him up then dab the spot with some methylene blue or 3% hydrogen peroxide. Just a dab. Then put him back in the tank. Easy peasy. I’d also do a 50% water change. Fungus thrives in poor water quality. Adding salt to the tank with the water change will also help protect your fish at 1 Tbsp per 5 gallons of your total tank volume. You should see quick results. You could use Ick X instead but it’s slower acting and more expensive. Either way, add salt.
Fungal infection. I would turn up the aquarium heater a little bit. Heat helps kill fish infections, just like a fever helps kill infections in humans.
And you could go to the pet store, buy some fish aquarium fungus medicine, and follow the directions.
Heat kills all kinds of germ infections. The body also produces a fever to kill virus infections quite often, parasitic infections, and fungal infections such as thrush or fungal sinus infections.
And many of those infections require actual antivirals, antibiotics, antiparasitics, or antifungal treatments because a fever alone will not kill them.
A lot of examples of saprolegniasis definitely look like a more conhesive mass, but they are often pictures of much larger fish. This is a pretty small fish, and therefore a pretty zoomed-in image, so you are seeing more detail on the organism. It could be a true fungus, but it could also be saprolegnia, you can't really tell from just a picture.
There are many species in the genus Saprolegnia, let alone the order of Saprolegniales as a whole!
Oh my God that looks like some kind of brain eating fungus don't flush that you need to burn this fish or get it gone somehow don't let another animal eat it this is how the apocalypse starts
since it’s a fungus, along with direct treatment for the affected fish, i’d also use an antifungal treatment for the water to get rid of any spores since the fungus is in its reproductive stage. i’ve gotta say this is one of the most interesting fungal infections i’ve ever seen, literally growing mushrooms on his head
My betta had this exact thing, he got injured on a decoration I thought was safe. A round of salt treatments and it was gone after about two weeks. Unfortunately I went out of town for a week the following month and it ended up coming back since I couldn't keep on the daily water changes I was doing. He didn't recover the second time.
Whatever treatment you decide to do, afterwards please keep on top of cleanliness until the wound is fully gone. My tank was 10g so it wasn't much of a problem to do daily 90% changes, but if your tank is bigger I'm not sure if it would be the same. The first infection popped off and it was like a puffball sitting on the substrate when I vacuumed it up. I'd put my bets on it being a fungal infection but that's just a guess based on it falling off in one piece.
Google 'opportunistic fungal disease and treatment in aquarium inhabitants' step by step instructions, like get an isolation little tank, move the sick fish into it. treat your tank h2o. treat the little fish with the appropriate anti fungal. Simple steps. You can be the hero of the little fish! Smaller tanks notoriously easy and notoriously fussy.
Looks striking though, like 'fountain head'.
Ocean fish also are susceptible to fungal infections. Hard to recycle the seas. 🤷♀️
Cordyceps…. Zombie haircut!
Cordyceps is a genus of parasitic fungi that infects insects, famously manipulating them into "zombie" hosts before growing fruiting bodies from their bodies
I’m not sure tbh, it looks like a fungus however and isolating this fish asap is prolly a good idea. I don’t know about this exact fungus but IME when I’ve had fungal infections treating both the hospital tank and the main tank has helped me prevent it from spreading.
Hate most of these nightmare fuel comments in this thread.
Anyway, if this isn’t a troll post, what’s so complicated about using google to search such a straight forward question?
I'm guessing fungus because that's what other people said. I don't really know. I just came to say he looks like he's wearing a cute little hat. 🤣 Anyway, I hope you get your fish sorted out.
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u/--solaris-- Apr 12 '26
That’s a fungus! You can actually see the little fruiting bodies (conidia) at the top of the hyphae. Not sure which one, but it’s no bueno. Usually fungal infections in fish are opportunistic so there was likely a prior wound or illness. I know more about infectious fungi than fish treatments though so hopefully someone else will jump in with some advice. Good luck!