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Kordon Methylene Blue 4 oz - Image 1
Kordon Methylene Blue 4 oz - Image 2
Kordon

Kordon Methylene Blue 4 oz

$4.39across 27 retailers
Model: MODEL-37344Color: Blues & PurplesUPC: 48054373442
Lowest at Amazon
$13.99 at Amazon
Price seen Feb 16, 2026
Lowest at any Popular Retailer
$7.60 at Bonanza
Price seen Jul 24, 2022

Where to Buy

Newest price seen: Feb 16, 2026
RetailerPriceLast seenBuy
A
AlotOfHome.com
$4.39Jul 31, 2023, may have changedBuy Now
P
PetMountain.com Pet Supplies
$4.39Jul 31, 2023, may have changedBuy Now
P
Petproducts.com
$4.73Jul 24, 2022, may have changedBuy Now
P
PetMountain.com Pet Supplies
$4.74Jul 24, 2022, may have changedBuy Now
T
That Fish Place
Sold by That Pet Place
$5.79Jul 24, 2022, may have changedBuy Now

Prices are collected from retailer listings; each row shows the date we last saw that price. Return and shipping terms are each store's standard policy from our retailer research (April 2026). Some products and categories have different terms, so check with the store before you buy.

Pros

  • •Effectively treats fungal infections on fish eggs, koi, goldfish, and aquarium fish.
  • •Works well for fin and tail rot as a separate bath treatment.
  • •Safely helps with ammonia poisoning, nitrite poisoning, ich, velvet disease, and mild bacterial infections.
  • •Proven track record of success and reliability according to multiple user experiences.
  • •Can be used as a dip or in temporary containers for targeted treatment without harming fish.
  • •Does not cause harm or health issues to aquatic animals when used correctly.
  • •Useful to protect fish during shipping or fry rearing by preventing bacterial and fungal growth.
  • •Noticeable improvement in fish behavior like swimming and eating after treatment.
  • •Considered a safe alternative to malachite green, avoiding burning or extreme irritation.
  • •Easy to use and supports healthy fry development and recovery.

Cons

  • •Stains tank surfaces, including silicone seals, making it unsuitable for direct addition to main aquariums.
  • •Should not be used directly in the main tank as it can harm beneficial bacteria essential for aquarium health.
  • •Works best for mildly sick fish; not effective for severely ill or damaged fish.
  • •Does not eliminate unpleasant fishy odors from aquariums.

Bottom Line

Kordon Methylene Blue is a trusted, go-to medicine for preventing fungal and bacterial infections in aquarium and pond fish, especially for targeted treatments like egg incubation, fin rot, and minor diseases. However, be prepared to isolate fish in a separate container since it stains tank silicone and can disrupt beneficial bacteria if used in the main aquarium. If you want a versatile, reliable treatment that’s safe for fish but requires careful application, this is a solid choice. For continuous aquarium treatment without staining concerns, you might want to look into alternative broad-spectrum aquarium medications.

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Discussion

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