5 Most Common Fish Diseases and How To Treat Them

[00:00:00] Welcome to this episode of The Aquarist's Edge, a podcast for home aquarists just like you. Learn more about how to keep a thriving aquarium and discover ideas and tips to give your aquarium the edge. And now, over to our host, Arthur Preston. Hi everybody, welcome back to The Aquarist's Edge. As you know, this is a podcast for everybody who loves standing in front of their tank with a cup of coffee, just watching their fish, and who wants to become a better aquarist

[00:00:29] and really create healthy, dynamic ecosystems in their aquariums. I'm really glad you're here. Thank you for spending some time with me this morning, or this afternoon, whenever you happen to be listening to this podcast. I'm really grateful for the community of keen aquarists who join regularly. And thank you for those who've been writing through the contact form on the website. It's really good to hear from you. Thank you to those who've been leaving comments on the YouTube channel and who've been putting reviews on Spotify, Apple Podcasts, and other places where you find your podcasts.

[00:00:59] It's really good to know that the work that's going into this podcast is making a difference to many, many people around the world who are just enjoying their aquariums. But now, one of the things that stops us from enjoying our aquariums is fish disease. Now, you know, picture this. You are looking at your aquarium one morning and your favorite fish, let's be honest, we all have a favorite, even if we pretend we don't, is covered in tiny white spots. What may be that its fins look like they've been through a shredder.

[00:01:27] Now, your stomach drops and that little question starts being asked, what is this and can I fix it in time before it's too late? If you've kept fish for more than a few months, you've had that morning. And if you haven't yet, it's coming. Because sooner or later, every single one of us deals with fish disease. It's not a sign that you're a bad aquarist. It happens to everybody.

[00:01:57] It will meet in freshwater aquariums. White spot, fin rot, fungus, velvet and dropsy. For each of these, I'm going to tell you what to look for, what's actually happening to the fish and exactly how to treat it. By the end, the next time you spot something odd, you will feel calmer and more capable instead of panicked. Now, just a quick favor before we start. Drop a comment telling me the toughest disease situation you've ever faced. Some of the best tips that I've learned come from listeners sharing their stories so we can all learn from one another.

[00:02:26] So go ahead, put a comment in the YouTube comment section or on the podcast app. Let's learn from each other. I often say that I think one of the beauties of being in community is the fact that we get to learn from each other's experiences. So let's hear your stories. Right, let's get into diseases. Before we can name a single one, though, here's the most important idea in this entire episode. In most cases, it's not the pathogen that causes the outbreak. It's the stress that opens the door.

[00:02:54] The parasites, bacterial and fungal spores behind these diseases are already in your tank right now. In a healthy, stable aquarium, they're sat in the background causing no trouble at all. What lets them win is a drop in the fish's defences. And the fish's first defence is its slime coat. That's the thin layer of mucus over its whole body. It's not only just a slippery goo. It's packed with antibodies and antimicrobial compounds.

[00:03:21] And it physically traps and sheds parasites before they take hold. When a fish becomes stressed, it produces cortisol. And chronic cortisol suppresses the immune system and thins the slime coat. Suddenly, that shield has gaps. And those background pathogens get their opening. Now, what causes the stress? Number one by a country mile is poor water quality. It's ammonia and nitrite burning the fish gills. Then, wrong parameters for the species,

[00:03:49] sudden changes, bullying tank mates or overcrowding, child support stress in new fish, and a poor diet. A fish health vet and a specialist at the University of Florida in the US, Dr. Roy Yanong, he has emphasised for a long time, if you read some of his work, that the foundation of fish health is management and environment. It's not your medicine cabinet. So, remember this. For nearly every disease today, step one of the treatment will be to check and fix your water. Now, that's not me being repetitive. It's where the battle's actually won.

[00:04:19] The medication is the cavalry. Clean, stable water is the army that's going to win the war. Now, one quick prep tip. Have a hospital tank ready before you need it. That would be a bare 40 or 60 litre tank with a sponge filter, a heater and a lid. It lets you treat a sick fish in isolation without dosing your entire display. Keep aquarium salt, meth blue, a good liquid test kit and an air stone on your shelf as well. And a general caution for everything that follows.

[00:04:48] Fish that don't have scales or that are delicate like lochas, corridoras and plecos are sensitive to certain medications such as malachite green and to salt. So, use half doses and always know your species before you medicate. Let's start with white spot, commonly known as ick. This is the one disease that we're all going to come across at some point. It's the most common disease in the aquarium hobby and you'll see small white spots about the size of a grain of salt

[00:05:17] scattered over the body and fins of your fish. And before that, you might notice flashing. No, no, no. Not that kind of flashing. This is flashing, meaning the fish are scraping themselves against dacre to scratch an itch plus clamped fins, rapid breathing if the gills are hit and lethargy. There is a key piece of knowledge here. Ick has a life cycle and that's how you're going to beat it. The white spot you can see is the feeding stage burrowed under the skin where your medication is not going to reach it.

[00:05:46] It matures, it drops off, it forms a cyst on the bottom and divides into hundreds of free-swimming babies that must find a fish within a day or two. And that free-swimming stage is the only point where the parasite is exposed and vulnerable. And that's why you never stop cheating when the spots vanish because the next wave is still coming. Now here's the clever part. The whole cycle is temperature-driven. At around 25 degrees Celsius, it takes roughly a week. So raise the temperature towards 28 to 30 degrees and you compress it to a few days,

[00:06:15] forcing those hidden stages out into the open where you can take them out. So raise the temperature gradually to around 28 to 30 degrees if your fish will tolerate it and add extra aeration because remember, warm water holds less oxygen. Then treat. Either heat plus aquarium salt and about 2 to 3 grams per litre for the hardier fish or a commercial ecumenication based on malachite green for heavier outbreaks. Keep cheating for a good week after the last part disappears and then vacuum the substrate during water changes to physically remove the cysts.

[00:06:45] With sensitive species, half the medication and get easy on the salt. The second disease is fin rot. Now, fin rot will sneak up on you. It starts as ragged, frayed fin edges, sometimes with a milky white or red margin. And left unchecked, the fins will recede, holes will appear and in severe cases, the rot will reach the entire fish body which is now very serious. But don't confuse this with fin nipping. Nipping leaves clean,

[00:07:15] torn bites on an otherwise healthy fish. But fin rot has fins that are ragged, discoloured and progressively deteriorating on the edge. The two may be linked because a nipped or injured fish is the perfect entry point for infection. But biologically, fin rot is usually an opportunistic bacteria that are always in the water and they only take over when a fish is weakened and the usual weakening agent is, yes, you got it, water quality. So step one, which often fixes mild cases on its own,

[00:07:46] test your water. Ammonia and nitrite at zero, nitrate ideally under 20 to 14 milligrams per litre and do a big water change and clean up detritus. For mild cases, add aquarium salt at around 1 to 2 grams per litre. For moderate to severe cases, move up to a proper antibacterial medication, ideally in your hospital tank and remove the cause. It could be sharp decor, a bully or overstocking. And the good news, fins will regenerate. Catch it early

[00:08:14] and correct the conditions and the fish will grow that tissue right back. The third disease is fungal infections. Now, true fungus will show up as fluffy, cottony white or grey tufts on the fish that are a bit like candy floss that's stuck to the fish. It's usually on injured tissue, the mouth or the fins. But here's the clarification that will save your fish. There's a bacterial disease called columnaris, nicknamed mouth fungus, that looks similar and constantly is confused with true fungus

[00:08:44] and it needs an antibacterial not an antifungal remedy. The rough rule, distinct fluffy tufts mean true fungus. Flat, pale, film-like patches that spread fast, especially around the mouth, mean that you should suspect columnaris and treat it as a bacterial infection. Columnaris moves quickly and can be lethal. So if you're unsure the fish is going downhill fast, treating for the bacterial version is often the safer bet. Now, assuming it's true fungus-like, film rot is opportunistic,

[00:09:13] colonising damaged tissue and thriving where there's decaying organic matter. So fix the water and remove any dead fish, uneaten food or rotting plant matter first. Then treat with an antifungal. Methylene blue is gentle and effective. Malachi green also works well. Support with a little aquarium salt and address the underlying wound or weakness so it doesn't return. Disease four is velvet, also known as gold dust disease. Now, velvet doesn't get talked about enough for how dangerous

[00:09:43] it really is, but partly because it's hard to see. It's caused by a parasite and it can wipe out a tank fast. The cyan is an extremely fine gold, yellow or rust-coloured dust all over the body, as if the fish were lightly sprinkled with gold powder. Unlike X distinct spots, velvet is a fine haze that's easy to miss under normal lighting. So, here's the pro tip. Turn off the lights and in the dark, shine a torch on the fish at an angle. The fine dust catches the beam

[00:10:13] and shimmers. Suddenly, you can see it. You'll also see flashing, clamped fins and rapid breathing, often before the coating is obvious. Now, the biology gives us a lovely weakness. The velvet parasite is photosynthetic. It harvests energy from light like a plant. So, darkening the tank actually starves it. Now, how often do you get to fight a disease by turning off the lights? So, the treatment is really to darken the tank completely. Cover it with a blanket if you can, raise the temperature

[00:10:42] modestly and increase aeration heavily because velvet will really damage gills. Then, medicate. Aquarium salt combined with darkness and warmth is a solid base. Often alongside a proper antiparasitic. Copper-based treatments are effective but remember that copper can hurt your shrimp, snails and plants. So, bear hospital tank is ideal and act fast. Velvet is not a weight in sea disease. The moment that the torch test is suggesting velvet, start treating

[00:11:12] and treat every exposed fish, not just the symptomatic ones. The fifth disease is dropsy and in many ways this would be the most serious. Dropsy isn't really a disease, it's a symptom. It's a fish whose body is filling up with fluid because something has gone badly wrong inside. The telltale sign is unmistakable. The body will swell, the scales stick out all over so the fish looks exactly like a pine cone. You'll often

[00:11:41] hear or see people talking about pineconing fish. This is exactly what it is. You'll also see bulging eyes, pale feces, lethargy and a loss of appetite. Underneath, the fish is failing to regulate its fluid balance, usually because of an internal bacterial infection attacking the organs, especially the kidneys. It's often the final result of long-term stress and poor conditions. Now, I've got to be real here. Once the scales are pinecunning, the prognosis is often poor. That's not a reason to give up, but your expectations

[00:12:10] need to be calibrated so you don't blame yourself if a fish doesn't make it. What to try and the earlier the better is to isolate the fish in a hospital tank with pristine, well-oxygenated water. We use Epsom salt, that's magnesium sulfate, not aquarium salt, at roughly 1-2 grams per liter to help draw off the fluid. Because the infection is internal, a medicated antibacterial food is the best delivery route if the fish is still eating. It can give warmth, quiet, and again,

[00:12:39] impeccable water quality. But dropsy, more than anything, is a prevention story. It's usually the final chapter of months of chronic stress. The real effective treatment happening long before that is, consistent water changes, stable parameters, good food, and an unstressed environment. Prevent the stress and you will rarely see dropsy at all. Did you notice the pattern running through all five of these? These diseases are opportunistic.

[00:13:09] The pathogens are already there. They only win when defense is dropped. So prevention isn't about killing pathogens, it's about keeping your fish strong enough that pathogens never get their opening. So three quick pillars. First, water quality. Regular water changes, a healthy filter, low nitrate, no overstocking and overfeeding. Second, quarantine every new fish for two to four weeks in a separate tank before it goes near your display tank. New fish are the most common way disease get in and this one habit prevents more tank wide outbreaks

[00:13:38] than anything else. Thirdly, and again, you've heard me say this often on the podcast if you've been a long time listener, observe your fish every day. Feeding time is your health check time. Key takeaways, most disease is opportunistic so a healthy unstressed fish is your best defense. Step one of nearly every treatment is fixing your water. Understanding parasite life cycles tells you why you keep treating past the point the symptoms vanish. Have your toolkit and hospital tank

[00:14:08] ready before you need them and quarantine every new fish. Now, you're far more equipped at the end of this episode than you were at the beginning. And so if this helps, please hit subscribe so you never miss an episode and leave a quick review. It really helps other fish keepers to find the show and as I asked at the beginning, drop a comment about the disease that gave you the most trouble and how you managed to solve it or even if you didn't. Folks, you will now see a link in the show notes and on the screen if you're watching on YouTube a link to buy me

[00:14:38] a cup of coffee. There are now over 100 episodes of Acuras Edge available in what is quite a comprehensive library of fish keeping advice and ideas. I would really value your support here. If you have a moment and you feel so inclined, please do go to the link that's given and buy me a quick coffee. That would be hugely appreciated. So thank you for spending time listening to another episode of Acuras Edge. I look forward to seeing you again next week when we will look at yet another topic to help us

[00:15:08] become better and more accomplished Acarists. And so until then, keep learning, keep discovering, keep enjoying this amazing hobby. Bye for now. That's it for this episode of the Acuras Edge. Please consider subscribing to this podcast so that you don't miss further episodes. We would love it if you would also rate and review the podcast as this helps make it visible to others. Until next time, keep learning and discovering and keep finding your Acuras Edge in this captivating and fascinating hobby.