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🛡️ Keep your aquatic friends thriving with Kordon’s blue power!
Kordon Methylene Blue is a 4-ounce liquid treatment designed to prevent fungal infections and treat parasites in both freshwater and saltwater aquariums. Made in the USA, it also reduces fish stress and supports oxygenation, making it an essential, safe, and versatile solution for maintaining healthy aquatic environments.

| ASIN | B00025646W |
| Allergen Information | Odor-Free |
| Best Sellers Rank | #36,883 in Pet Supplies ( See Top 100 in Pet Supplies ) #19 in Fish Medication & Health Supplies #351 in Aquarium Water Treatments |
| Brand | Kordon |
| Brand Name | Kordon |
| Customer Reviews | 4.7 out of 5 stars 3,730 Reviews |
| Global Trade Identification Number | 00048054373442 |
| Included Components | KORDON #37344 Methylene Blue-General Disease Prevention Treatment for Aquarium, 4-Ounce, |
| Item Form | Liquid |
| Item Type Name | KORDON # 37344 METHYLENE BLUE 4 OZ |
| Item Weight | 4 Ounces |
| Liquid Volume | 4 Fluid Ounces |
| Manufacturer | KORDON LLC |
| Manufacturer Part Number | 048054373442 |
| Model Number | MODEL-37344 |
| Pet Type | Fish |
| Target Species | Fish |
| UPC | 048054373442 |
| Unit Count | 4 Fluid Ounces |
T**N
Fungus, not sure what's going on. Fish need extra oxygen.
I've been using methylene blue for a long time. I use it for fungus on my fish if I notice a little bit starting or if their coat starts getting a little slimy. I usually try this before I try anything else. Or if for some reason my nitrates or nitrite spike I'll use this a little bit for some added oxygen if my fish start getting stressed out or are already stressed out. This has always worked very well for me. I've never had any fish stressed out about it. No headshaking ever like what happens when I add metronidazole or praziquantal or other meds. Methylene blue has also never hurt my pond plants. I don't pour it directly in my pond. It's always been in the hospital tank. I did recently use it when I bought some water hyacinth from a pond shop. I always bring them home and put them in a container with grow lights and heat to make sure that they don't have a bunch of snails and dragonfly nymphs and whatever else there is on those things. Well, I ended up having a bunch of baby fry fish hatch from these plants. About a week later the little fry baby's started turning white and dying. I wasn't really sure what to due because I didn't want to kill these plants that I just spent a couple hundred dollars for and I didn't want to let the baby fish die. I added some methylene blue and some nitrofuranzone together with the baby fry and with the plants which also had snails, snail eggs, dragonfly nymphs on them and the white that I guess was fungus on these little baby fish I can't really tell because they were so small. I did it once left it in there for two days and then the partial water change and I didn't have any more baby fry fish die and my Hyacinth plants are still growing and still blooming. Some even flowered out purple flowers right away. So it didn't hurt them at all. I was kind of disappointed about these plants and there had to have been something on them for these baby fish to get this but not only that the guy told me that they had goldfish in with the plants. I called And asked him after all these baby fries start hatching. I think something that people should think about, and I don't know if people actually just buy plants and throw them in their ponds. I always did and I always ended up coming down with some kind of ailment around that time and I just thought it was a change in temperature, water parameters. But if the place where you buy the plants has goldfish or other fish in with them they have a fungus or bacterial infection and you bring those plants home and throw them in your pond you're going to bring that stuff into your pond. So for now on I quarantine my plants. Back to the methylene blue. It's definitely blue. I've never had it stain anything. I took pictures of what it looked like. It took pictures of my fingers after completely just dipping them in the stuff. And then the last picture I took was me washing my hands one time. It was almost completely off. Once I take a shower it's completely gone. I've never had the methylene blue stain anything that I've ever had permanently. I think that having the methylene blue around in case you have something going on and you don't know what it is is a fish lifesaver. You can at least be able to use it just in case you need to. It is better than not having anything at all. If I wouldn't have had the methylene blue on hand along with the nitrfurazone at the time I'm pretty sure all the little fish would have been dead. Because that morning when I checked on them they had nothing white on them. Later that afternoon is when I started noticing it. About four of them died. So that's my methylene blue story. I'm not sure how it would stain if you got it like on your rings or your jewelry or anything but it does eventually go away when I get it on my hands and stuff.
K**N
Great Medicine for my Freshwater Fish
Worked great on my sick fish, kept the fish in the Methylene Blue for a few days and slowly started to do water change to ease it's transition back into normal water. Just follow the instructions and be careful not to spill as it can stain counter tops.
M**.
... a treatment for white cotton fungus and ich with great results. The second time my order arrived the ...
I have ordered this product twice to use to as a treatment for white cotton fungus and ich with great results. The second time my order arrived the seal in the bottle was broken, but I believe it was only due to rough shipping and it has graciously been replaced for no charge. Be forewarned that methylene blue may stain your aquarium ornaments, filaments, epoxy, and tubing. It is also not recommended for use with plants because of it's mechanism of action which basically inhibits their ability to uptake nitrogen. But most of the hardier plants will quickly bounce back as long as the exposure is limited. I use methylene blue because malachite green and other treatments like CopperSafe are toxic to inverts. I have had no issues with my white skirt tetras, otocinclus catfish, mickey mouse platys, plecostamus, shrimp or snails with this product, and the results are fast. I usually treat my tank for a duration of 4-5 days, beforehand I vacuum out my gravel and do a water change. Then I put my carbon filter in a gallon ziploc bag with Reverse-Osmosis water and fish flake to break down and feed the bacteria. Keep it in a warm place out of direct light, I use a cardboard box. Feed your fish as you normally would and I highly recommend getting an air pump if you haven't already if you are treating sick fish or ich and you need to raise the temperature. Keep the tank lights off and out of direct UV light for 3-4 hours to avoid your fish being stained blue because of their cells absorbing it with the UV. Do not worry about the color of your water. After treatment when you replace your filter the water will turn back to clear in a day or two as long as you have a good filter and do a 25% water change. The dye is not permanent in the water. I also recommend using methylene blue to treat new arrivals while acclimating them. Methylene blue's primary use is as an anti-fungal and in this capacity it works wonders. I have personally had great results with it while treating ich and other common ailments. This is also a great dye to use if you are staining slides while using a microscope and you want to do a gram-test. This is a great product that I have found to be very rare to find in stores so I will be definitely be purchasing more in the future.
B**V
Effective, but a little leaky
It appears to work rather quickly against Saprolegnia on Koi. Note: This bottle is a little leaky, and the stuff stains like heck. Use rubber gloves and keep the bottle in a bag in a bucket, and make sure it doesn't come into contact with things you don't want blue.
K**D
Saved my betta
Saved my betta from dropsy. This stuff is a life saver. It is very safe as long as you dose correctly. And my betta is happy and healthy now because of it!
H**R
My fish looks so much better and hes back to his old self
My betta was suffering from some kind of bacterial infection and I immediately ordered this because Ive heard great things. He's my first pet fish and I was especially worried when his energy started to decline and he wasnt his usual self. So when this came in the mail, I immediately set up a hospital tank and followed the instructions for dosage according to the tank size. I didnt notice a smell at all, but the water definitely turned deep blue. Its very pretty, but it will stain anything. My fish immediately started to perk up within the day. Within the next few days, he was acting normally and his fins even started filling out more. I recommend this absolutely!! Its easy enough to use, and safe for sick fish when used correctly.
S**.
Extremely Effective Cure
Kordon Methylene Blue is an essential chemical for any aquarist. Methylthioninium chloride treats eggs to ensure they are not lost to fungal overgrowth. Methylene Blue can also be used for the treatment of nitrate poisoning and ammonia, as well as an antiparasitic, antifungal. It can also serve as an aquarium safe disinfectant. Some disorders that I have used to treat Methylene Blue are as follows: Nitrite Poisoning, Ammonia Poisoning, Ichthyophthirius Multifilis, Oödinium Pilularis, Swim Bladder Disorder, Fish Stress, and Egg Fungus. To identify some of these conditions I will list some basic symptoms as you can easily identify the disorder. Nitrite Poisoning - Fish gasp for breath, brown or tan gills, rapid gill movement known as gilling. Ammonia Poisoning - Fish gasp for breath, purple or red gills, lethargic - to which the fish may lay on the bottom, red streaks may appear on the fins or the body. Ichthyophthirius Multifilis (AKA ICK) - Small white spots resembling sand or substrate, fish scratches against objects and damage their slime coat. Oödinium Pilularis (AKA Velvet) - this disorder is caused by a parasite. The cycle is rough on the fishes body and as a high contamination rate, so it is important to treat this as soon as possible. Swim Bladder Disorder - Fish struggles to maintain proper position, floats upside down, swims with tail higher than their head. Fish Stress - Prophylactic treatment of fish under stress, usually due to being move. Fish may seem fatigued with a loss of appetite and discoloration. Egg Fungus - Serves as a safe and mild disinfectant for fish eggs. Methylene Blue can be used with crustaceans including but not limited to shrimp, crabs, and snails. However, the chemical should be introduced slowly and with great caution. Additionally, I do not recommend using Methylene Blue with live plants since it will kill healthy bacteria and oxygen deprive the plants causing them to be damaged or in most cases killed. It's important to use it with caution with crustaceans or live plants and should only be used to short periods. It is important to note that Methylene Blue should not be used concurrently with water conditioners. If you do treat the water with a conditioner wait 30-minutes before adding Methylene Blue. Also, discontinue the use of carbon media in filters while treating with Methylene Blue otherwise, the carbon will remove the chemical to which it will not affect. Lastly, Methylene Blue will be absorbed by porous materials such as coral, rock, and wood. In most cases, it will also permanently color the silicone sealant in aquariums. After all treatments, a complete or partial water change should be made and don't forget to put back the activated carbon in the filter.
H**A
5 stars
good
Trustpilot
2 weeks ago
2 weeks ago