Home / Fish / Melafix


By | Last Updated: 23rd February 2023

What is Melafix used for

Melafix is an all-natural antibacterial treatment, prepared from certain tea tree species [2], effective against various gram positive and gram negative bacterial infections [1]. It is generally given to freshwater or saltwater aquarium fishes to help treat conditions like fin rot, tail rot, mouth fungus (cottonmouth), eye cloud, and pop-eye [1].

Quick Information


Check Price on Amazon

Brand name: Melafix® [1]

Type: Natural fish antibiotic [1]

Ingredient: Melaleuca tea tree oil (1.0%) [4]

Is it FDA approved: No [4]

Availability: Over the counter [4]

Who can take it: Aquarium fish [5]

Available forms: Liquid [3]

How does Melafix work in aquarium fishes like bettas, goldfish, guppies, and gourami

Due to the antimicrobial property of tea tree, Melafix penetrates through the disease-causing bacteria’s cell-walls and damages the structure of their cell membrane. Therefore, it helps eliminate bacterial infection by stopping their growth and preventing them from reproducing [7].

Does Melafix really work

While it may be useful for healing physical abrasions, open wounds, and triggering re-growth of tissues and fin rays damaged by bacterial infections [1, 2], it may as well prevent bacterial diseases from spreading through and contaminating other fishes in an aquarium [1]. However, there are some conflicting opinions regarding its efficacy against bacterial and fungal infections [8].

Can it be used for treating ich

Melafix alone does not treat ich (also called ick or white spot disease) in freshwater aquarium fishes. But, a combination of Melafix, Pimafix, and aquarium salt may be beneficial [3].

Melafix dosage: How much to give

Consult with a vet about the safe dosage before adding Melafix into your aquarium. The dosage commonly used is 5ml per 10 U.S. gallons (37.8 liters) of fish tank water [1].

How to apply

When you add new fishes to an aquarium, give the prescribed dosage regularly for 3 days [1]. For open wounds and bacterial diseases in fishes, you may be advised to continue putting it to your aquarium daily, for 7 days (or longer if the condition persists) [1, 3]. Perform a 25% water change after 7 days [1].

During the treatment, your vet may recommend removing the carbon filters and turning off UV sterilizers and protein skimmers because UV light might hinder the effectiveness of the medication while the protein skimmers might remove the medicine particles through filtration, rendering the treatment useless [7].

Possible side effects

It does not usually cause any harmful side effects, and studies have shown the medication can be safely used to treat delicate fishes, including clown loaches, discus fry, and tetras [4]. It is unlikely to cause any harm to aquarium plants, and reef-aquarium invertebrates like anemones and corals [4].

When given as per a vet’s recommendations, it is also not known to adversely harm the biological filter, discolor the water, or alter the pH [3]. During the treatment, a mild foaming may occur, but it is not harmful to the aquarium environment [4].

This antibiotic is not given to fishes meant for human consumption [4]. It has a chemical ingredient known to cause cancer and birth defects in humans [4].


    1. MELAFIX® – Apifishcare.com
    2. Melafix an Antibacterial Fish Treatment – Watergarden.org
    3. API Melafix Freshwater Fish Bacterial Infection Remedy 237 ml – Petsathome.com
    4. LABEL: API MELAFIX – melaleuca liquid – Dailymed.nlm.nih.gov
    5. Fish Antibiotics and Other Aquarium Medications – Saltwateraquariumblog.com
    6. The mode of antimicrobial action of the essential oil of Melaleuca alternifolia (tea tree oil) – Onlinelibrary.wiley.com
    7. Melafix® FAQs – Apifishcare.co.uk

Leave a Reply

Your email address will not be published. Required fields are marked *

38 − = 29