Seachem SulfaPlex 10g



Seachem Sulfaplex 10g

Absorbed through gills, Seachem Sulfaplex treats and heals fish with fin rot, reddish streaks, fur coat, mouth rot, fungus. The medication is suitable for freshwater and saltwater fish.


SulfaPlex is an effective and safe treatment for many bacterial, fungal and protozoan infestations in the aquarium. While it can be used in both freshwater and saltwater, it is particularly effective against the common bacterial and fungal infections of freshwater fish. It is also among the gentler antibiotics, and great for treating fish that are already stressed. It is easily removed with carbon and does not impair nitrification.


Active ingredients: sulfathiazole (69%) Inactive ingredients: excipients (31%)


SulfaPlex is appropriate for treating a variety of bacterial, fungal and protozoan infestations. Below are some of the more common diseases treatable with SulfaPlex. Be aware that many diseases and infections share similar physical and behavioural symptoms, e.g. clamped fins, lesions, loss of appetite.

Fin Rot

  • Bacterial infection: Fins appear shredded, frayed, or decaying. Fin Rot is frequently mistaken for damage from fin-nipping fish. Contrary to the name, this is actually caused by bacteria, not fungus.
  • Suggested Treatment Period: 3 weeks or until infection clears
  • Special Considerations: Fin Rot is often found as a secondary infection (that's an infection that started because the fish was already sick). Make sure to check for additional infections.

Hemorrhagic Septicemia

  • Aeromonas hydrophilia: Reddish streaks in the fins near the body or under scales. Common in goldfish. Associated with overcrowding and stress, particularly in goldfish and koi. It can also be caused by a virus.
  • Suggested Treatment Period: 3 weeks or until infection clears
  • Special Considerations: This infection is strongly linked to crowding and poor water conditions. Make sure your fish have clean water and plenty of space.

Fur Coat Syndrome

  • Discoloration of tissue, development of grey or brown fur growing on body, listlessness and loss of appetite. This is an unsightly infection that most often appears in bettas.
  • Suggested Treatment Period: 3 weeks or until infection clears
  • Special Considerations: This infection progresses rapidly and must be treated immediately if you expect your fish to recover. It is very strongly linked to poor water conditions and low temperature in betta bowls.

Mouth Rot

  • Columnaris: Damaged fins, ulcers and yellowish patches on gills, tissue on head and mouth eaten away. This infection appears gruesome, but is entirely treatable. It is common to see fungus-like tufts around the face and mouth in addition to deterioration of tissue. It is essential to catch this disease early to prevent long-term damage.
  • Suggested Treatment Period: 3 weeks or until infection clears
  • Special Considerations: Columnaris is very contagious. If possible, remove the infected fish to treat separately in a hospital tank.


  • Symptoms: Cotton-like tufts of white fibre. Almost always a secondary infection (appears when fish is already infected with a disease). True fungal infections, while unsightly, generally do not pose an immediate danger to fish.
  • Suggested Treatment Period: 3 weeks or until infection clears
  • Special Considerations: Fungus is relatively easy to treat and almost never fatal on its own. However, it tends to appear as a secondary infection, meaning there is a more serious disease causing the fish to be susceptible to a fungus.


Dosing in Water

Remove all invertebrates - these are extremely sensitive to medication. Turn off UV filters, ozone filters, and remove chemical filtration like MatrixCarbon and Purigen. Use 2-3 measures (included) per every every 40 L (10 US gallons). Repeat this dose every 72 hours for a maximum of 3 weeks.

Dosing in Food

SulfaPlex is most effective when used in the water, but it can also be added to the food. Feed the medicated food mix (recipe below) every day until the infection clears or up to 3 weeks.

1 scoop SulfaPlex

1 scoop Focus

1 tbsp food (preferably pellets or frozen food)

A few drops of water if using a dry food

To enhance palatability use with GarlicGuard or Entice.

After Treating

When the treatment period is over, SulfaPlex can easily be removed using activated filter carbon like MatrixCarbon. It does not linger in the substrate or filter media of the tank.