Fritz Maracyn® Two is a specially compounded, broad-spectrum antibiotic effective against a wide range of pathogenic bacteria associated with ornamental fish disease, making it an excellent first choice when the cause of illness isn’t clear. It targets gram-negative organisms primarily, but also fights some gram-positive and fungal infections, giving it coverage across multiple types of disease in one treatment.
Active Ingredient: Minocycline
For the treatment and control of septicemia, bacterial fin and tail rot, and cotton wool disease in freshwater and saltwater fish caused by Flavobacterium columnare, Aeromonas punctata, and Aeromonas hydrophila bacteria. Can also be effective against dropsy, internal infections, and other secondary infections, such as wounds from injuries or parasites.
Cotton Wool (Columnaris)
Fin and tail rot
Dropsy
Popeye
Gill disease
Septicemia
Consult a veterinarian or fish expert for assistance in diagnosis of disease-causing organisms and treatment options.
All suspected bacterial infections should be treated immediately.
Symptoms of possible bacterial infection can include clamped fins, swollen eyes, heavy or rapid breathing, patchy coloration, change in swimming behavior or corner-hiding.
Bleeding or red streaks on body, ulcers may also be present
Swollen, bloated body, protruding scales and/or clamped fins
Protruding eyes, may be cloudy or hazy
Swollen, discolored gills, gasping for air and a decrease in activity
Treatment course lasts for five days with a water change on day six. Note the day 1 dose is higher. Complete the full treatment course even if visible signs of infection disappear.
Day one: Add the contents of one packet per 5 gallons (19 L).
Day 2–5: Add the contents of one packet per 10 gallons (38 L) per day.
On day six, perform a 25% water change
If symptoms improve but do not completely disappear, repeat five-day course once more.
May be safely used along with other treatments: Coppersafe, Maracyn, and Maracyn Oxy.
Dividing up our powder packets accurately for use in smaller tanks can be tricky, and to get the proper dose we recommend making a concentrated solution that is much easier to measure, see video below
Treatment may inhibit nitrifying bacteria. Monitor ammonia and nitrite levels during treatment.
Maracyn is compatible with many fresh and saltwater species, equipment and most Fritz products, see below for details.
Species | Compatible? | |
|---|---|---|
 | Saltwater fish |  Yes |
| Freshwater fish | Yes |
| Snails and other invertebrates | Yes |
| Koi and goldfish | Yes |
| Live plants including pond plants | Yes, some plant species may show temporary yellowing |
| Bettas | Yes |
| Coral | Yes |
Equipment / Products | Compatible? | Notes | |
|---|---|---|---|
 | FritzZyme Nitrifying Bacteria | Yes | Always monitor water quality and re-dose FritzZyme after treatment to restore biological filtration. |
| Fritz water conditioners | Yes | |
 | Maracyn | Yes | Safe to use at the same time |
| Maracyn Oxy | Yes | Safe to use at the same time |
| Coppersafe | Yes | Safe to use at the same time |
Ask our experts, we’re here to help!
| Item # | Size | Treats up to | Case QTY | UPC |
|---|---|---|---|---|
| 75047001 | 10 powder packets | 100 gallons (380 L) | 24 | 080531470015 |
| 75047002 | 20 powder packets | 200 gallons (760 L) | 12 | 080531470022 |
| 75047003 | 100 g | 1,000 gallons (3,800 L) | 1 | 080531470039 |
| 75047051 | 400 g | 4,000 gallons (15,142 L) | 1 | 080575047051 |
