Fritz Maracyn 2

Fritz Maracyn 2 is a broad-spectrum minocycline antibiotic for ornamental fish, the gram-negative counterpart to original Maracyn. It targets the bacteria behind fin and tail rot, popeye, gill disease, dropsy, septicemia, and red streaking, and its packet form keeps dosing simple in freshwater or saltwater systems.

Browse our full medication lineup or the rest of our Fritz range.

What It Treats

• Gram-negative bacterial infections: fin and tail rot, popeye, gill disease, dropsy, septicemia, and hemorrhagic red streaks on the body or fins.
• Absorbed through skin and fins: minocycline reaches the infection even when sick fish refuse food, which is when most antibiotic-laced feeding fails.
• Freshwater and saltwater: safe in both systems when dosed as directed.
• Pairs with original Maracyn: for gram-positive infections like columnaris and bacterial gill disease, reach for Fritz Maracyn. The two can run together for broad-spectrum coverage when the culprit is unclear.

Dosing

• Day 1: add two packets per 10 gallons of water.
• Days 2 through 5: add one packet per 10 gallons every 24 hours.
• Day 6: perform a 25 percent water change. Repeat the course once if symptoms improved but have not fully cleared.
• Remove activated carbon during treatment, keep aeration strong, treat in a quarantine tank when possible, and always confirm with the directions on your box.

Specifications

Recommended Pairings

• Cover gram-positive infections with Fritz Maracyn.
• Rule out water quality first with a kit from water testing.
• Recondition after treatment with Seachem Prime.

FAQ

How do I know if I need Maracyn or Maracyn 2?
Fuzzy white patches, mouth fungus, and gill disease point to gram-positive bacteria, that is original Maracyn. Rotting fins, dropsy, bloating, and red streaking point to gram-negative, that is Maracyn 2. Unsure? Bring us a photo and we will help you choose.

Why is the first dose doubled?
The loading dose brings the water column up to a therapeutic concentration fast, and the daily packets keep it there for the rest of the course.

Will it hurt my biofilter?
Minocycline mainly targets gram-negative bacteria, which includes some nitrifiers, so watch ammonia and nitrite during treatment. Treating in a quarantine tank protects your display tank's cycle entirely.

My fish stopped eating. Will it still work?
Yes. Maracyn 2 is absorbed through the skin and fins, so it reaches the infection even when the fish refuses food.