Chloroquine Phosphate, Quinine Hydrochloride-Sulfate for Aquarium

[Carlrs]

FROM:

https://www.aquarium-medications.com/2018/12/chloroquine-phosphate-quinine.html

Chloroquine Phosphate, Quinine Hydrochloride, & Quinine Sulfate are anti-malarial drugs that are also often very effective for single cell ecto-parasites in fish, especially Cryptocaryon, Oodinium, Brooklynella, and occasionally Ichthyophthirius Multifilis and flukes in freshwater

Quinine drugs work by causing a pH elevation in intracellular organelles of parasites, this is thought to disrupt the intracellular transport of membrane components and macromolecules, and phospholipase activity leading to cellular failure of these parasites.

Chloroquine was developed from Methylene Blue (also used starting in 1891 as an anti-malarial drug) & Quinine Sulfate in 1934. The formula of Chloroquine & Methylene Blue is also similar (MB: C16H18ClN3S / Chloroquine: C18H26ClN3).

In marine aquariums, Chloroquine Phosphate is generally the better choice over Quinine Sulfate. Chloroquine Phosphate is more effective from my experience (but also more easily and fatally overdosed). When combined in a synergistic combination with Pyrimethamine, as in the product "AAP Marex", it is even more effective for treatment of Oodinium as well as other Ectoparasites and Flukes (Pyrimethamine is generally used to treat serious parasite infections [toxoplasmosis] of the body).

Chloroquine Phospate is a drug that degrades quickly in water and must be pure to be effective, with most aquatic sources are not 99% pure.
With this in mind be mindful of the discount aquarium product seller placebo product "New Life Spectrum's Ick Shield Pellets", even assuming properly soaked with pharmaceutical grade 99% pure Chloroquine Phosphate (which is doubtful), this product simply cannot work because Chloroquine Phosphate has only been proven to successfully target the free swimming stage of EXTERNAL parasites. Which is why you must dose the powder in a hospital tank. There is no proof it is effective on trophonts feeding on the fish. Even if food soaking were somehow effective on preventing trophonts from attaching, you'd have to be sure each & every one of your fish ate it for 72 consecutive days.
Bottom line, AVOID this product.

The above referenced from this article:
Aquarium Medications Part Two; Quinine

This combination found in AAP Marex works more quickly than chemical treatments such as copper since it immediately acts on the parasite, including in gill filaments, which copper and many other chemical treatments only act on free swimming stages of many Ectoparasites.
This synergistic Chloroquine Phosphate/Pyrimethamine combination is the fastest acting treatment I have ever used for Oodinium, although I have often found a follow up treatment with Copper or keeping the main aquarium without fish for 4 weeks will improve long term results (as copper seems to have more long term permanent killing power).
This combination of Chloroquine Phosphate/Pyrimethamine is also an excellent treatment for gill flukes in freshwater and can generally be safely combined with Praziquantel for severe cases.

Further Reading: Marine Oodinium Disease | Brooklynella & Amyloodinium Ocellatum